* enable_cmake_compat to enable compatibility for specific cmake versions
* added required files for 2.8.2 and 2.8.6 (taken from a recent cmake version)
cmake/compat_2.8.3 contains files required for cmake versions < 2.8.3
and CheckCmakeCompat includes them if necessary.
CMakeParseArguments.cmake and FindPackageHandleStandardArgs.cmake are
taken from the modules shipped with cmake.
