instead default to activate dune-common's

also fix default max for intel's MIC platform

For some reason cmake errored out if Likwid was not found on that
platform.

This reverts commit ba71a7857d78f85ff258834f7820928c253102af
since the update required cmake stuff in common (>=2.4)

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

Drop support for override and final keyword discovery since all supported
compiler understand those by now. Further use of DS_OVERRIDE or DS_FINAL
will trigger a compile error.

This reverts commit 2e8a29f9f02fae28920147e17fc0406a57ca8524
and should work now since we're shipping the FindEigen3
script that's apparently missing from some current
cmake distributions

This reverts commit 043fbca5cadb4e4ef7909df0049aef350bb61d89.

refs #5

This reverts commit b5e571fc9ad2240d510514566c0946b2cce23426.

At the moment it is not trivial to configure a debug build with e.g. -O2.
Upon calling make cmake is called and the CMAKE_CXX_FLAGS_DEBUG are
appended to any given CMAKE_CXX_FLAGS, thus overriding any -O? given there.
Since the desired debug flag might vary from compiler to compiler
(-O0, -Og) anyway I propose to remove the -O? entirely from the debug
flags. Please revert or voice opinions!