[uggrid][bugfix] Don't add MPI flags explicitly

if you compile Dune with a sequential UG, but with MPI, the old configuration added MPI
to the CPPFLAGS. This implied that GridFactory< UGGrid<...> > use the MPI version of
CollectiveCommunication. When you now tried to run a seqential program, i.e. you didn't
add the MPI flags, you got an MPI error when creating a UGGrid using the GridFactory, as
you tried to call MPI command (in UG part of libdunegrid) without calling MPI_Init
(as MPIHelper used the fake version). Instead of adding the MPI flags explicitly, we rely on the
buildsystem. The m4 test adds the MPI flags to teh UG flags, if a parallel UG and
MPI are found.
(cherry picked from commit 6f67f970b2dd45d3fc7f7cc3fef39d6bad3825fb)

Signed-off-by: Christoph Grüninger <gruenich@dune-project.org>
[buildsystem,bugfix] Fixes list of *.msh *.geo files to be distributed and installed

There were quite some files below doc/grids/gmsh missing in the tarballs. This patch
adds these and makes the file lists for patch friendly
(cherry picked from commit cc17e4141df5600cc8958e64f5cf91445bcae857)

Signed-off-by: Christoph Grüninger <gruenich@dune-project.org>
[release, buildsystem] Allow reuse of grid tests for 3rdparty grids with installed dune-grid.

The source of the grid test of dune-grid never got installed. Given their genericity they are
quite useful for downstream grid developers. These developers might want to be able to test
their grid even with an installed dune-grid module. To facilitate this the commited patch now
installs the test source.
(cherry picked from commit eae3c5ff0c50e01072506ebc7df63fd53da920f1)

Signed-off-by: Christoph Grüninger <gruenich@dune-project.org>
[buildsystem,release] Generate cmake package configuration files with autotools
(cherry picked from commit b70c98aa43f4124a7e059da46f4ec985ec536aba)

Signed-off-by: Christoph Grüninger <gruenich@dune-project.org>
[autotools,bugfix] correct path to cmake directory

There was just missing the $(top_srcdir) var.
(cherry picked from commit 995998a4e09c390ed32eb321685fc588be33e683)

Signed-off-by: Christoph Grüninger <gruenich@dune-project.org>