- don't know exactly why it works like this, I suspect it is
due to the DEPENDENCYCHECK dune/xt/common/test/CMakeLists.txt
that depends on the xtcommon variable defined in the header
listing

see http://clang.llvm.org/extra/clang-tidy/

`add_format` now only takes one argument: a directory that is used
the base dir for recursive globbing files into clang-format
Usages of the macros are adjusted accordingly. It's still possible to
use it multiple times in a project, if one for whatever reason
does not wnat to throw it at the source root. Only one `format`
target will be generated either way, with one subtarget per
`add_format` invocation.

refs #30

i.e. bring back testtools workarounds

users will need to use add_forced_doxygen_target instead of
add_doxygen_target in their appropiate CMakeLists.txt

The problems remain however how to enable alugrid in the tests...

This reverts commit e90dfa4e46491e1c909995c7dc74bf5f0c68b9a1.

Setting the GRIDTYPE with FORCE does not make any sense of course
(since it overrides any manual change immediately).

This really enables header listing of all dependent modules for me. cmake
takes noticeable longer though - if this bother too many people we have to
revert.

This really disables all warning from dependent modules for me.

These can be now changed using ccmake. Additionally default to ALUGRID_.
This made HAVE_ALUGRID true in the testcases for me.

this adds dunestuff to the DUNE_LIBS