[release][doxygen] Removed doxygen error.

There entries in doxyerror.log about undocumented function
parameters and parameters that had a wrong name in the documentation.
This patch fixes this.
[release] Improved documentation of the parallel section.

VariableSizeCommunicator now appears in doxyen and the parallel
index sets are a subsection of the parallel section.
[release,cmake] Install data files to package specific datadir like with automake

E.g. the files in am are now installed to share/am/dune-module instead of share/am.
[release,buildsystem] Fixes list of files to install.
[release,automake] Fixes occurences of dune-istl in install directories.

When moving the documentation of the parallel index sets from dune-istl
to dune-common, we forgot to adjust the installation directories accordingly.
This patch fixes this situation.
[release,automake] Fixes installation of files below am.

The am_DATA variable was set to EXTRA_DIST which contained
CMakeLists.txt. Therfore CMakeLists.txt was installed.
This patch fixes this by listing files to install in am_DATA
and using EXTRA_DIST only for those files that are otherwise
not distributed. Suprisingly, some files from am_DATA have to
be listed there, too.
[release,automake] Stop overriding docdir needlessly.

docdir is variable of automake and its by default set to $(datadir)/doc/dune-common.
Therefore there is not need to set it here.
[release,cmake] Install manpage of dunecontrol.
[release,cmake] Fixes installation directory of DoxyFile.
[release,cmake] Corrects the location of Doxyfile in the package configuration.

This completes the last patch where we moved its installation directory by
reflecting the new location in the package configuration.
[release, am2cmake] Fixes not traversing directories listed in SUBDIRS after test.
[release,cmake] Use uppercase for CMake type in variables.
[release,bugfix] Fixes running the doxygen documentatio with every make call.

The cause for the problem was the introduction of cmake/modules. This caused
the find statement to always print something. This patch simply excludes
cmake/modules from the result with grep -v.
[cmake,release] Corrects setting of HAVE_* variables.

For generating the config.h file we use the HAVE_* variables instead
of the CMake ones *_FOUND, Unfortunately, we sometines to not set
HAVE_* to the value of the *_FOUND vriable but to its name. Usually
we only query whether these variable are set at all. While
this often (except for psurface) does not pose a problem, it is semantically
wrong. Therfore this patch fixes this.

Kudos to Ansgar for pointing to this problem.
[bugfix] Fixes GMP test.

Previoulsy CMake always fails to find the __gmpz_abs symbol on my machine, even though it is clearly there.
The test used check_symbol_exists. According to the documentation, check_symbol_exists tries to include the
second argument into a test program to check whether there is a prototype for the first argument, so as the
second argument is a binary, that can't really work... This patch switches over to use check_library_exists.
[CMake,release] Remove double slash (//) in path for headercheck.
[release] Install dune_cxa_demangle.m4
[bugfix][autotools] Fix broken --without-parmetis.

This fixes FS#1404.
[bugfix,cmake] Fixes precendence issues in module path

When working with installed modules, the cmake scripts and
modules of the current module should take precendence over
any installed ones. This was not the case before this patch.

Furthermore, modules downstream in the
dependency tree should be able to overwrite tests in  modules
that they depend on. This patch more caredfully crafts the
CMAKE_MODULE_PATH to reflect the module dependency in it.
[cmake,bugfix] Fixes requiredness of module

Previously, dependencies were not correctly searched for as
required packages. This patch fixes this.