Linux OpenAL support

Hi.
This branch allows Linux users to use OpenAL instead of FMOD by using make with `OPENAL=1`. There is also a way to disable vorbis support with `NOVORBIS=1`. OpenAL simple audio engine is approximately the blackberry simple audio engine.
Ubuntu users may want to install `libvorbis-dev libopenal-dev libalut-dev` to make it work.