Improve comments.

Previously we checked whether the extracted Version evaluated to
True. Unfortunately, there lazy people like me that like use a version
of 0 for testing, which evaluates to False and breaks configure.
With this patch we allow 0 to and just test wether the version consists
of characters.

A variable was not correctly escaped during creation of the file
cmake/modules/Makefile.am causing the error message:
"duneproject: line 914: datadir: command not found."

This patch now correctly escapes it.

duneproject failed miserably when run with only installed modules. With
this patch we correctly setup the pkg-config and dunecontrol path to
handle this situation. In addition we fixed various issues with the newly
created modules and they now build as exspected.

With new modules there were cases where cmake/modules was not in the
modules path which made configuration fail. This patch fixes this case.

Due to testing the wrong directories some variables where missing in the
package configuration files. This patch fixes this.

The clutter the output.  I can't believe anyone really wants to see
the friend relationships in doxygen.

Somehow, the vector version of CollectiveCommunication< MPI_Comm >::prod
passed std::plus to allreduce (instead of std::multiplies). This patch
corrects this flaw.

Previously some of the pathes (e.g the multiarch ones) took precedence
over the others. But as with same some of the pkgconfig files are installed
below lib/<multiarch> and others (if there is not object library) are not.
With this patch all possible install locations of pkgconfig files are added
to the path if they exist.

With openSuse 12.3 (Doxygen 1.8.5) the generated documentation contains
lots of huge graphs which show the include dependency graph of a file.
This lead to large tarballs of 155 MiB compared to 50 MiB with this
patch.
With Debian Wheezy (Doxygen 1.8.1.2) the tarballs did not blow up in
file size. Scanning the Doxygen change log did not enlighten me and
I remain puzzled why the graph were never built.

INCLUDED_BY_GRAPH is changed to prevent the same behvior for future
releases. We currently do not include these graphs and this change
makes the configureation consistent with the result.

The compiler might exit with nonzero exit code if given non-existent
options. Therefore we need to use set +e during this to make dunecontrol
to continue running even the options are not supported.

Some ^[$BLANK] or [^[$BLANK]^'], where $BLANK is space followed by tab
did not work as a capturing statement in some cases (e.g. opts files
with CONFIGURE_FLAGS="CXX='bla'"). After this patch we use [$NOBLANK]
with NOBLANK=^$space^$tab which works. In addition the other patches
form feature/posix-sed-dunecontrol have been backported to close flyspray
1401.

Unfortunately gcc-4.4 does not support --print-multiarch.
Therefore we fallback to cc -v and grep for the target in this case.

DuneCmakePackageConfigHelpers.cmake -> DuneCMakePackageConfigHelpers.cmake

Apparently it is not available with some older versions of CMake.
Therefore we provide a poor man's alternative for it, if it is
not there.

Debian uses multiarch-triplets (e.g. i386-gnu-linux) when installing
object libraries. These are installed to lib/$multiarch-triplet and not
to lib directly. In CMake this concept is partially supported by
GNUInstallDirs.cmake by setting CMAKE_INSTALL_LIBDIR to
lib/$multiarch-triplet. Unfortunately, this is only half the way through
as we also install libraries that do not differ between architectures (e.g.
our shell libraries.

This patch addes multiarch support for CMake to the best of my knowledge,
which might be limited, though:

- All not architecture dependent libraries are installed below the variable
  DUNE_INSTALL_NONOBJECTLIBDIR, which defaults to lib, but might be adjusted
  by the user.
- If the module ships an object library then the pkg-config and CMake package
  configuration files are installed in lib/$multiarch-triplet/pkg-config and
  lib/$multiarch-triplet/cmake/modules, respectively.
- If not then they are installed in lib/pkg-config and
  lib/cmake/modules, respectively.

Note that for autotool no such difference exists and always the latter approach
is used.

Previously aclocal did not find the DUNE macros when they were installed to
the new location. This patch fixes this by adding the path to this list of
include paths if it is available.

Somehow I missed some files when committing. this patch fixes this.

Previously, the macros were installed to $(datadir)/cmake/. As we have
some macros in DUNE that might also be in other packages
this may cause conflicts in package managers. With this patch we install
them to $(datadir)/dune/cmake to resolve this issue. Together with the
last patch this will resolve problems  outlined in flyspray
task 813
https://dune-project.org/flyspray/index.php?do=details&task_id=813
I apologize for givin the wrong task number in the previous patch.

Previously, the macros were installed to $(datadir)/aclocal. As we have
some macros in DUNE that are also installed for some Linux distributions
this caused conflicts in package managers. With this patch we install
them to $(datadir)/dune/aclocal to resolve this issue outlined in flyspray
task 1409
https://dune-project.org/flyspray/index.php?do=details&task_id=1409

When unpacking the tarballs, the time stamps are preserved, but the
access time of the files might be set differently. In addition during
configure Doxyfile is always created. This resulted in some files being
newer than the doxygen-tag in the tarball and triggered building the
documentation. This patch fixes the problem for me by only checking the
modification time and excluding Doxyfile.