- openal: revise header inclusion: OpenAL/al.h for osx and AL/al.h for
others. if windows builds want openal output, Creative OpenAL 1.1 SDK
headers aren't under AL/, but with OpenAL-soft, all headers are under
the AL/ directory (http://kcat.strangesoft.net/openal.html) therefore
no problems.
- cmake: now that openal header inclusion is revised, no need to add
the al.h directory among the header paths. besides, I was using the
TARGET_INCLUDE_DIRECTORIES function which requires cmake-2.8.11+ and
I was not comfortable with it.
cmake cleanups. (mostly replacing CMAKE_CURRENT_[SOURCE|BINARY]_DIR
with CMAKE_[SOURCE|BINARY]_DIR )