OS X versions older than El Capitan (10.11) do not define MAP_ANONYMOUS,
but only MAP_ANON. On the other hand, MAP_ANON is deprecated on Linux.

So add a preprocesser switch to make both happy.

[cmake] extract bottom block from config.h.cmake

For dune-grid a bottom section is needed to place the Grid Type magic at the bottom of the config.h
file in derived modules.

In this patch a /* begin bottom */ ... /* end bottom */ block from each module's config.h.cmake file and placed
at the end of the collected config.h file.

This resolves the problems from FS#1713 if the same branch is applied in dune-grid.

See merge request !19
(cherry picked from commit b1e924e6)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

[CMake] Rewrite C++ standard detection

This is a complete rewrite of the existing C++ standard version test
that tries the various `-std=c++xy` flags and tries to figure out which
version of the standard to enable.

The existing version has a few problems:

- it is not really extensible to newer standards, those will just lead
to a deeper and deeper nesting of `if` statements.

- More importantly, there is no way to say: I want C++11, but not C++14
  (or, in the future, I want C++14, but not C++17). Being able to do so
  is important for testing and compatibility reason.

- There is no easy way for downstream modules to require a newer version
  of the standard than the core modules.

The new version of the test separates the logic from the data (versions,
flag names, compiler test sources) and just iterates over lists of that
data, in descending order to make sure the newest available standard
gets picked. The numerical value of that standard is stored in the
variable `CXX_MAX_SUPPORTED_STANDARD` and the test stops. If the test
fails to find a working combination, it issues a warning to the user and
only records support for C++03.

The test can be influenced by two CMake variables:

- `DISABLE_CXX_VERSION_CHECK` already existed in the old version of the
  test. It completely disables all testing and requires the user to
  manually set `CXX_MAX_SUPPORTED_STANDARD` to the correct value.
  Moreover, any required compiler command line switches have to be
  manually added to `CMAKE_CXX_FLAGS`.

- `CXX_MAX_STANDARD` defines the maximum version of the standard that
  the build system will try to enable. With this new switch, it becomes
  possible to limit the compiler to an older version of the standard
  than what it could theoretically support. For now, this defaults to
  C++14.

In order to allow module authors to easily state their minimum version
requirements, there is a new CMake function
`dune_require_cxx_standard()` that any Dune module can call to require
support for at least a given C++ standard:

```
dune_require_cxx_standard(MODULE "dune-functions" VERSION 14)
```

If the compiler doesn't meet the requirements, the function will report
the required and the actually available standard versions and abort with
a fatal error.

Moreover, it knows about CXX_MAX_STANDARD and will tell the user if the
value of that variable is below the requirements. This avoids desperate
users that have a shiny beta of GCC 6 with C++17 support wondering why
their own module using shiny C++17 concepts stubbornly fails to build...

This fixes #16, and a backport to 2.4 will also be a fix for #15.

See merge request !46
(cherry picked from commit 31252385)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

FindSuiteSparse.cmake: Correct `HAVE_SUITESPARSE_${_component}`

See merge request !47
(cherry picked from commit 1b545b39)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

C++11 defaults destructors to noexcept.
Good catch, GCC 6!

Adjusted to check for availability of noexcept specifier, as that is not
a given in 2.4.

(cherry picked from commit 45797c46)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

Thanks to Elias Pipping for figuring this one out - it (re)closes the
absolutely ancient #flyspray/FS185.

The point of the matter is that posix_memalign() is not allowed in this
context according to the relevant standards, so we use mmap() instad.

`mprotect` can only be used for `mmap`'ed memory

Makes testdebugallocator pass on OS X, too.

See merge request !43
(cherry picked from commit 6467775c)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

Backport suitesparse test to 2.4

This is a straightforward backport of the new SuiteSparse test from
master by simply cherry-picking all commits that touched either
`FindSuiteSparse.cmake` or `FindUMFPack.cmake`. On top of that, I
removed the deprecation warning from the old UMFPack test and extended
it to automatically populate `SuiteSparse_ROOT` from `UMFPACK_ROOT` if
only the latter is set.

This fixes #14 

See merge request !40

This addresses warnings such as

  'const' type qualifier on return type has no effect

(cherry picked from commit 1de4cb89)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

feature/use MPI_Type_create_hindexed instead of MPI_Type_hindexed which is deprecated for MPI>=2

:)

See merge request !29
(cherry picked from commit dea4e7d0)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

[dunecontrol] Check less often the version for module dependencies

Similar to update, status, svn, git, exec, and bexec don't check
whether the versions for dependencies are fulfilled.

This could fix #9

See merge request !28
(cherry picked from commit 47255e4f)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

Fix FieldMatrix::rightmultiply()

This addresses an issue mentioned in #5 and additionally turns runtime checks into compile-time checks whenever possible.

See merge request !22
(cherry picked from commit 71e2e4b8)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

Feature/fix shadow warnings

If you have better name suggestions, please tell me and I change the names.

See merge request !21
(cherry picked from commit 394c5cde)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 2abb3bd4)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 47830f03)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit c232686d)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 2125b283)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

Test complex<T> for floating point T only

The standard leaves (the effect of instantiating) complex<T> for more
general T unspecified.

While we're at it, kill duplicate tests and add long double to the list.

This fixes bug flyspray/FS#1726: Now also with clang 3.7 and libstdc++ 4.9.2 on Debian 8.2, the test fvectortest can be compiled again.

See merge request !11
(cherry picked from commit 627fc0b0)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit b5db5759)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

GitLab readable contribution guide, license and README

Adding the `.md` extension enables rendering of the files, which is much nicer.

Also ported the contribution guide from the User Wiki.

Renamed COPYING to LICENSE.md because that is the name that GitLab looks for to display it nicely on the project starting page.

If this one is accepted, I will do the same for the other core modules.

See merge request !5
(cherry picked from commit 633391ff)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 49879f16)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 1906105f)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 28762f7b)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 4526cad8)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

The section is empty since the code was split into the dune-geometry
module.

(cherry picked from commit c37cd9cb)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 60459f97)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 927edfc7)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

floating comparisons

(cherry picked from commit 94a327ac)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit a1bd9774)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 2f6aa790)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 7369e156)
Signed-off-by: Steffen Müthing <muething@dune-project.org>

- Disable deprecation warning
- Populate SuiteSparse_ROOT from UMFPACK_ROOT if necessary