Added a simply system to keep record of the x most recently played
OpenALSoundS (where x is the number of simulataneous sources allowed) and,
in case a new sound refuses to play, stop()'s the least recently played
sound and attempts to play it again (but only once, to prevent endless
loops in case something else prevents the sound from playing).
Added removal of disposed sounds from the buffer
Merge pull request #890 from Amyntas/master

Added a simply system to keep record of the x most recently played