Remove deprecated headers

See merge request !147

[ci]Use dune-matrix-vector from new location

See merge request !144

[cleanup]Avoid deprecated interfaces from the core modules

See merge request agnumpde/dune-fufem!143

Here we derived from `BoundarySegment` and additionally
from `VirtualFunction`. I cannot see any reason for the
latter. Hence we can remove this as base class to avoid
a deprecation warning.

Using `MCMGMapper::update()` without a grid view argument is deprecated.

Deprecate header dune/fufem/concept.hh

See merge request agnumpde/dune-fufem!142

This has been superseded by `dune/common/concept.hh`.

Deprecate Dune::Fufem::formatString()

See merge request agnumpde/dune-fufem!141

* Remove unused include of `formatstring.hh`.
* Replace usage of `Dune::Fufem::formatString()` by `Dune::formatString()`.

This has been superseded by `Dune::formatString()` long time ago.

[test]Reenable test of SubgridL2FunctionalAssembler

See merge request agnumpde/dune-fufem!140

* Avoid nasty double assignment `a=b=0`
* Provide `QuadratureRuleKey` with appropriate order to L2-assemblers
* Provide appropriate order to H1-assemblers
* Reenable test of `SubgridL2FunctionalAssembler`
* Reenable test of `SubgridH1FunctionalAssembler` for `UGGrid`
* Avoid short circuit evaluation of test results. This implicitly
  disabled checks if a previous one was failing.

The checks for `ALUGrid<3,3, Dune::simplex, Dune::nonconforming>` are still
disabled, because the failure mentioned in
https://git.imp.fu-berlin.de/agnumpde/dune-fufem/-/issues/14
persists.

[test]Simplify CMakeLists.txt

See merge request agnumpde/dune-fufem!139

This cmake file was overly complicated for historical reasons.

Remove some Dune::VirtualFunction related stuff

See merge request agnumpde/dune-fufem!138

This is based on the old function interface and can be replaced
by a simple `std::map<:std::string, std::function<Range(Domain)>>`
for the new interface.

This class implements the old function interface
and is no longer needed.

These classes implement the old function interface
and are no longer needed.

These classes implement the old function interface
and are no longer needed.

[test] Reenable serialization test

Closes #20

See merge request agnumpde/dune-fufem!136

!119 was intended to 'Remove a work-around for clang 5 and earlier'.
In fact this was a work-around for newer clang versions. It added the
test if the compiler was either not clang or not newer than clang 5.
By removing these lines, the test was not enabled at all.

This patch reenables the test without the work-around. Hopefully the
CI gained a newer boost version in the last 4 years, such that there's
no need for the work-around.

[ci]Stop using images with debian-10 (oldstable)

See merge request agnumpde/dune-fufem!137

* Use `dune:2.8-debian-11-gcc-10-20` for testing against the 2.8 release
* Use `dune:git-ubuntu-20.04-clang-10-20` for testing againt master with clang.
  This helps to avoid an issue with clang-7 and boost-serilization in debian-10.

Use localIds instead of globalIds

Closes #22

See merge request agnumpde/dune-fufem!116

Remove ConstantFunction

See merge request agnumpde/dune-fufem!122

This still uses the deprecated function interface, but at least allows to get
rid of the function implementation. Adjusting the assemblers is a separate task.

It implements the VirtualFunction interface, which has been deprecated
since before the release of Dune 2.7.

Remove Python support for VirtualFunction/VirtualDifferentiableFunction

See merge request agnumpde/dune-fufem!121

Both have been deprecated since before Dune 2.7.

Remove deprecated method Fufem::istlVectorBackend

See merge request agnumpde/dune-fufem!134

It still relied on the old basis implementations.

From now on, use Dune::Fufem::MassAssembler instead.