[raudio] ADDED: SetAudioStreamBufferSizeDefault()

There could be some cases where we need to define the internal audio buffer size, now it's possible.

RENAMED: InitAudioBuffer() to LoadAudioBuffer()
RENAMED: CloseAudioBuffer() to UnloadAudioBuffer()

Renamed some defines and reviewed some comments.

src/raylib.h

@@ -1428,6 +1428,7 @@ RLAPI bool IsAudioStreamPlaying(AudioStream stream);                  // Check i
 RLAPI void StopAudioStream(AudioStream stream);                       // Stop audio stream
 RLAPI void SetAudioStreamVolume(AudioStream stream, float volume);    // Set volume for audio stream (1.0 is max level)
 RLAPI void SetAudioStreamPitch(AudioStream stream, float pitch);      // Set pitch for audio stream (1.0 is base level)
+RLAPI void SetAudioStreamBufferSizeDefault(int size);                 // Default size for new audio streams
 
 //------------------------------------------------------------------------------------
 // Network (Module: network)