* S_Init -> S_InitSfxChannels because it did mostly SFX anyway
* S_MusicPlaying, S_MusicPaused, S_MusicName, S_MusicExists new status methods
* I_MusicPlaying, I_MusicPaused
(cherry picked from commit f5f0b5e76c2fd405c8cc895dde653c5ed2652622)
* In s_sound, they are merged to one method as well, but there are still two separate digvolume and seqvolume variables
* Simplified Dig/MidiMusicDisabled in s_sound
* Method reordering
(cherry picked from commit 701cc5a7dd1dfead87a42ec7558c9fa6a1deb193)