Audio: remove VoIP and platforms specific hacks

VoIP will be reintroduced and platforms specific hacks will
hopefully not be needed if we use OpenAL Soft everywhere
Audio: WIP on the rewrite.

* Introduce ALObjects: a minimal wrapper to hide OpenAL calls
* Introduce Samples: load raw samples from files (= buffer)
* Broken
  * Streaming audio (VoIP and maybe something else)
  * Buffers are not freed (=> no handling of memory pressure evnets)
  * Can only compile with VoIP off
  * Ambients loops are not synchronized
  * Entity loops restart the loop after leave-entering the maxDist