Changed the documentation in Common/Float.h. Exposed details about OpenAL in the documentation of SoundState and SoundEffect. Added the method SoundState::MakeOpenALContextCurrent. Added the method SoundEffect::IsPlaying. Added documentation example code for SoundEffects (SoundEffects.cpp). Added error checking to SoundEffect's constructor and destructor. Exposed details about PHYSFS in the documentation of FileSystem.