Changes

ALAudioSink: Enhance description re 'AudioFrame' and 'frameDuration'; Drop unused field 'avgFrameDuration'.

ALAudioSink: Use float in seconds for duration (AudioFormat and 'avgFrameDuration') to avoid losing precision when dealing with stats, averages etc

ALException: Suppress serial warning

Sound3D: Further OO wrapper to be used in ALAudioSink: Context locking, ALCcontext recreation, ..

Context
- Recursive context locking (only 1st shall do native makeCurrent, only last shall do native release)
- Access to the current Context instance (thread local storage)
- Obey "One context can only be current on one thread,
        and one thread can only have one context current!"
- ALCcontext recreation within lock, allowing to change native OpenAL specifics via attr list
- ALCcontext creation (initial) w/ attr list

Device
- Retrieve name if default name null has been given
- Expose device name
- Allow to open() again

Source
- Allow lazy creation w/ invalid ID
- Allow create() post instantiation (for a single source)
- Throw ALException in all queued buffer methods as they are crucial
  in multithreading streaming.
- Add queue buffer with OpenAL buffer-id int[] arrays variant
  to be used w/o Buffer

Listener
- Fix (get|set)Orientation() API doc: It's 'at' vector, then 'up' vector.

General:
- Have toString()
- Added versatile AudioSystem3D.check*Error(..)

Earlier Sound3D changes
- 7f73d50c90d05cf7388f23977ca956a4933019ad
- 64b40bd4359cad46ebf62751ea342d80205bd98b

ALAudioSink: Use and expose Sound3D object, allow user app to deal w/ JOAL/OpenAL easier and reuse Context context locking

Context locking logic has been fixed and moved to Sound3D Context class (beside many other transparency changes),
see commit afb386e13fd00fde1401d4551ee4790b1f6d5e09.

This also aligns w/ AudioSink API change of Gluegen commits
- c04726720a57f8db42f2621ad58ff3bd42006c63
- 6a74d16a805a4204093972bb91361b2aa633065c

Promote SimpleSineSynth to API (util) from Synth02AL, allowing user to have a simple sound source to test