Draft of MP3 decoder based on libmad. It's already works!
MP3 decode routines added to ISoundSample class.
Correct locating of MP3 audio frames. Ignoring of ID3v1 and ID3v2 tags.
Some basic routines for MP3 audio streaming added but not yet tested.
Fixed some ISound bugs with sound frames mixing and streaming.
Also added required ISound::ReleaseChannelsByCallback routine.
And some minor fixes to ResourceManager.
Fixed serious ISound bug with streamable chanels.
Also some minor codestyle changes in some other code.
Another small fix to ISound.
Fixed ISoundChannel SetCurrentPosition issue.
Finished MPEG Layer III decoder realization Closed #111
Change resources and plugins unload order/
Merge pull request #172 from DGLE-HQ/mp3_decoder_plugin

MPEG Layer III decoder plugin.