No longer repeatedly invoke malloc for retrieving memory. Some operations still
leak memory (notably audio streaming). We introduce notion of Transient and
Permanent storage. Transient memory is used for data in memory that is
temporarily allocated (i.e. graphics for that frame's output), and permanent as
more like game state storage.
We now give out pointers from a pre-allocated block of memory, so we have no
allocation cost and benefits of reduced memory leaks. The transient block gets
reset every frame. Any memory allocated within is cleared at no cost simply by
rearranging the base pointer of the memory block.
Use event queue to decouple audio playback from the battle system. Switch
back to using begin and end attack within the entity update loop for
conciseness.
On intermittent stop of OpenAL playback deleting the buffers without
unqueuing the current buffers is an invalid operation, causing invalid
audio states on alGetSource().
Audio can be played with 1 call, audio_beginVorbisStream which
encapsulates the initialisation of the renderer and release on finish.
OpenAL is quoted to have a limitation of around 32 sources. Audio
renderers hence acquire a source slot on playback and immediately release
on finish. This ensures that sources are held optimally and minimises the
possibility of saturating the available sources.
Renderers hold an index to the source list, which the index reveals the
source ID for their use.
