Merge branch 'static-treepath' into 'master'

ref:staging/dune-typetree\> We introduce an alias StaticTreePath<i,...>
referring to the corresponding HybridTreePath<integral_constant<i>,...>.

The old (superseeded) static TreePath<i,...> is now deprecated and will be
removed after 2.7.

The StaticTreePath will stay as a convenience alias.

(related to [#10])

See merge request [!75]

  [#10]: gitlab.dune-project.org/NoneNone/issues/10
  [!75]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/75

We introduce an alias StaticTreePath<i,...> refering to the corresponding HybridTreePath<integral_constant<i>,...>.

The old (superseeded) static TreePath<i,...> is now deprecated and will be removed after 2.7.

The StaticTreePath will stay as a convenience alias.

Merge branch 'feature/merge-treepath-classes' into 'master'

ref:staging/dune-typetree\> This removed the explicit implementation of
TreePath<i...> and makes it an alias for HybridTreePath<index_constant<i>...>.
While it is intended that TreePath is completely removed, there might be
incompatibility issues if downstream modules switch to HybridTreePath but
their users still use TreePath. Such issues should be avoided by this patch.

See merge request [!71]

  [!71]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/71

Merge branch 'feature/drop-fallback-std-stuff' into 'master'

See merge request [!73]

  [!73]: Nonestaging/dune-typetree/merge_requests/73

Merge branch 'feature/remove_child_storage' into 'master'

ref:staging/dune-typetree\>

### Summary

Cleanup the child(),childStorage() node member functions and corresponding
free functions and removed type aliases ChildStorage and ConstChildStorage
from node implementations

### Details

-   The child-storage is in all node implementations a shared_ptr of the child
    type. This is even implicitly assumed in several methods, like setChild().
    So it does not make much sense to allow flexible child storage types.
-   The child-extraction methods `childStorage(node, i...)` are not
    consistently implemented like `child(node, i...)` and several type aliases
    or free functions are missing, so this MR cleans this up.
-   The member functions node.childStorage(i) were not implemented correctly
    in all node implementations. But they cannot be removed right now because
    they are used in the tree transformation methods.
-   The node.childStorage(i) now consistently take an integral-constant or a
    runtime index as first argument. This allows for more generic
    implementations.

### To Do

-   [x] Check compatibility with dune-pdelab
-   [x] Check compatibility with dune-functions

See merge request [!72]

  [!72]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/72

removed free function childStorage() and type aliases ChildStorage and ConstChildStorage from node implementations

[!65] removed unnecessary constructors and use implicitly generated constructors instead in TreeContainer

Merge branch 'issue/treecontainer_constructors' into 'master'

ref:staging/dune-typetree\> This MR essentially applies the rule of zero to
the TreeContainerVectorBackend class and allows to copy this container.

See merge request [!65]

  [!65]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/65

Merge branch 'feature/compatible-hybridtreepath' into 'master'

ref:staging/dune-typetree\> This allows to use
HybridTreePath<index_constant<i>...> as a drop in replacement for
TreePath<i...>. It also replaces two remaining use cases of TreePath by their
HybridTreePath analogue. This implements [#10].

As a consequence TreePath could be dropped if all downstream modules have
switched to HybridTreePath. Once this transition was made we can consider
getting rid of some of the functionality introduced here. E.g.
Dune::TypeTree::TreePathSize<HTP>::value could be easily replaced by
HTP::size().

See merge request [!69]

  [#10]: gitlab.dune-project.org/NoneNone/issues/10
  [!69]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/69


Closes #10

Merge branch 'issue/tree_container_tests' into 'master'

See merge request [!66]

  [!66]: Nonestaging/dune-typetree/merge_requests/66

Merge branch 'do-not-use-dune-shared-ptr' into 'master'

ref:staging/dune-typetree Up until dune-common 2.7, Dune::shared_ptr would
also work (and point to the std implementation). Post-2.7, only
std::shared_ptr is possible.

See merge request [!67]

  [!67]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/67

Up until dune-common 2.7, Dune::shared_ptr would also work
(and point to the std implementation).  Post-2.7, only
std::shared_ptr is possible.

Merge branch 'feature/bump-to-2.8' into 'master'

See merge request [!64]

  [!64]: Nonestaging/dune-typetree/merge_requests/64

Merge branch 'feature/improve-treecontainer' into 'master'

ref:staging/dune-typetree Add alias TreeContainer using a meta function to
determine the per node value

-   Add support for TreeContainer<LeafToValue,Tree> where LeafToValue<Node> is
    the value associated to a node of type Node.
-   Add a manual lambda implementing the LeafToValue<Node> transformation by
    default constructing the values. This is needed because you cannot use a
    lambda expresion in a type alias.
-   Rename the existing TreeContainer<Value,Tree> alias to
    UniformTreeContainer<Value,Tree>. This is an **interface change** but:
    -   This is needed because you cannot have to templates of the same name.
    -   The new name is better.
    -   The old interface was not published in a release so far.

See merge request [!61]

  [!61]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/61

Merge branch 'feature/mailing-list-as-maintainer' into 'master'

ref:staging/dune-typetree As Steffen steps down as the maintainer of
dune-typetree and nobody claims this his or her project, I propose to set the
Dune developer mailing list as the dune.module email address. Further, there
will be no single maintainer to be asked for approval. Typetree will be like
the core module, were everybody does as he thinks it is the best. We help each
other by discussions and comments. I assume that especially users of
dune-functions and PDELab will follow the development and contribute further
improvements or features.

@smuething @dominic @oliver.sander @carsten.graeser @christi Would that be ok?

See merge request [!62]

  [!62]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/62

* Add support for `TreeContainer<LeafToValue,Tree>` where
  `LeafToValue<Node>` is the value associated to a node of
  type `Node`.
* Add a manual lambda implementing the `LeafToValue<Node>` transformation
  by default constructing the values. This is needed because you cannot
  use a lambda expresion in a type alias.
* Rename the existing `TreeContainer<Value,Tree>` alias to
  `UniformTreeContainer<Value,Tree>`.
  * This is needed because you cannot have to templates of the same name.
  * The new name is better.
  * The interface was not published in a release so far.

This simply calles the default constructor of the stored
container class.

Merge branch 'bugfix/deterministic-child-transformation' into 'master'

ref:staging/dune-typetree As a side effect of using parameter packs in the
implementation of the transformation behaviour of composite nodes, the
traversal order on the tree was not defined. The commit reimplements the
transformation such that evaluation order of children is left to right.

See merge request [!59]

  [!59]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/59

Merge branch 'bugfix/deterministic-child-transformation-cpp14' into 'bugfix/deterministic-child-transformation'

ref:staging/dune-typetree This should make [!59] compatible with C++14.

See merge request [!60]

  [!59]: gitlab.dune-project.org/NoneNone/merge_requests/59
  [!60]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/60

Merge branch 'feature/remove-vintage-treepaths' into 'master'

ref:staging/dune-typetree This MR (based on [!18]) removes DynamicTreePath,
MutableDynamicTreePath, MakeableDynamicTreePath, TreePathType::mostlyStatic,
and TreePathFactory. None of them is used any more in dune-typetree and
dune-pdelab when applying the modernization of the tree traversal algorithms
in [!18].

The key is, that the modernized tree traversal only uses HybridTreePath which
nicely does the job. The only other remaining tree path implementation is the
fully static TypeTree::TreePath. Getting rid of this one is harder, because
TreePath<i...> is used heavily as template parameter in dune-pdelab.

Notice that I'm not sure if removing all those implementations without
deprecation is a good idea. Hence this MR mostly serves for demonstrating how
this could be cleaned up. However, if the removed stuff is considered
internal, one may consider merging directly (after [!18] of course).

See merge request [!21]

  [!18]: gitlab.dune-project.org/NoneNone/merge_requests/18
  [!21]: gitlab.dune-project.org/staging/dune-typetree/merge_requests/21

As a side effect of using parameter packs in the implementation of the
transformation behaviour of composite nodes, the traversal order on the
tree was not defined. The commit reimplements the transformation such
that evaluation order of children is left to right.

Merge branch 'feature/update-author-list' into 'master'

See merge request [!58]

  [!58]: Nonestaging/dune-typetree/merge_requests/58