Re-jigger Makefile.
Re-jigger Makefile.

- Uses more standard $CFLAGS and $CPPFLAGS variables to populate the set
  of flags to build with.
- Allow extending compilation and linking flags with
  $CPPFLAGS_DEBUG_EXTRA, $CPPFLAGS_FAST_EXTRA, $CFLAGS_DEBUG_EXTRA, and
  $CFLAGS_FAST_EXTRA.

Closes #40.

OpenMusicKontrollers/chimaerad,OpenMusicKontrollers/chimaerad,OpenMusicKontrollers/chimaerad,OpenMusicKontrollers/chimaerad,OpenMusicKontrollers/chimaerad,OpenMusicKontrollers/chimaerad