Added logic to force Clang to be the compiler on Apple/Xcode.  Also added a number of cmake options that appeared as advanced.
Re-added stdint include to datatypes.h, keeping the new solution for MSVC.
Merge branch 'master' of github.com:BlackToppStudios/Mezzanine
Removed a number of needless semi-colons and commas where they really don't belong/don't make sense.