* Add MUSIC_AUDIO_NONE to MusicContextType and format fixes
- Useful to check the context type to see if the format is recognized. Defaulting to wav causes issues where formats are assumed to
be wav.

* Fix memory issues with LoadMusicStream and UnloadMusicStream
- Set ctxType and ctxData even if the format fails to load.
- Set ctxData to NULL if it fails and check for null inside UnloadMusicStream.
- Change RL_MALLOC when loading formats to RL_CALLOC to prevent undefined behavior.
- Add NULL check when unloading xm file.