Soundfile resource (#252)
* SoundFile class to grab properties from HSound
* Add SoundFile.GetSamples
* Use PrecacheSound to get sound handle
* Getting samples has to be async
* Comments
* Bail out of getting samples if we failed to load the source
* Add CSfxTable refs for SoundFile, release them on loop end and exiting
* Rename ISound to VSound_t