* I_GetMusicType() -> I_MusicType()
* Wrap MIDI volume hack in #ifdef _WIN32

(cherry picked from commit a7d51bf8)

* S_MusicInfo method to retrieve name, flags, and looping

(cherry picked from commit f6ec93198f0dcfa1d053cca88172c3e3c7ba310c)

(cherry picked from commit 4aa100aa575cc7fc14a743085222c806ba2c714a)

(cherry picked from commit 86f151db)

(cherry picked from commit 07738fb0bcf640a4349337373f451fe68e024b2a)

(cherry picked from commit d5ec38815968e267aceb59a48a6cb6d3292c0b69)

* 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 f5f0b5e7)

(cherry picked from commit 9fb9386f84b3739fe765a78bcb9683eb7e98bc36)

* 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 701cc5a7)

(cherry picked from commit 14b393ab)

* Revised S_PlayMusic arguments
* Now music plays again!

(cherry picked from commit 55f3803e4b9f8104c90cc6c769d54121e5bac0b8)

(cherry picked from commit 9a5fc5f6)

Colormap code cleanup

See merge request STJr/SRB2!275

R_CreateColormap2 and R_MakeColormaps have been made obsolete, it's just R_CreateColormap now, like it used to be!

With that, I moved R_CreateColormap2's exclusive software colormap malloc code to R_CreateColormap, and merged the two software-only blocks of code into one. I also disabled any unneeded variables and fixed a preprocessor-related goofup

Fix for HOM removal in non-green resolutions

See merge request STJr/SRB2!273

Yo Screen So Wide y Is Invalid

See merge request STJr/SRB2!271

v_video Killed The r_radio Star

See merge request STJr/SRB2!270

Zalloc Potter and the Death-Free Hallows

See merge request STJr/SRB2!269

Lighting fixes? Plane and simple!

See merge request STJr/SRB2!268

Introduce a temporary measure to enable the old stuff, minus one of the most obviously terrible bugbears of yesteryear. Let it be known that any downstream poirt will almost certainly toggle this ASAP.

Clean up a bunch of v_video.c functions that previously exhibited unfortunate side effects when run in non-green resolutions.

* V_DrawFixedPatch and ilk:
	* Change the offset of V_FLIP so it's not one screen-pixel off where its non-flipped sprite would have started being drawn from.
	* Write to x and y as well as desttop so that anti-screen-overflow checks later in the function behave properly with non-green resolutions.

* V_DrawFill:
	* Reduce number of operations performed upon `c`.

* V_DrawString and ilk:
	* Offset the left and right boundary checks in non-green resolutions such that you can actually draw stuff to the left of basevid screen x coordinate 0.

* Stop orphaning their memory. They ARE PU_LEVEL, so they'll disappear eventually, but, like... it's not good memory management practice to just *orphan* them when you're literally never going to do anything with them ever again. Y'know?
* Make ghosts spawn properly on slopes.

* Fix that thing where ALL transparent FOF planes were continuously fullbright unless encased in a fog which disables sprite fullbrightness, which was long-hated by many people in the community!
	* For backwards compatibility, setting flag 1 in that fog field (which is probably the most common "in-the-wild" usage of this feature) will continue to make objects un-fullbright.
	* For situations where you desperately want the behaviour to be enabled, you can apply fog flag 2.
* Change the fadestart and fadeend range in which colormaps are generated.
	* The problem HERE was that the darkest light level reached by generated colormaps was actually slightly brighter than the darkest level reached by normal colormaps.
	* The typo I fixed does have SOME basis in fact - standard colormap lumps are 34 (33 in 0-indexing) long rather than 32 (31), but whoever wrote this didn't realise that the code for generating them didn't do it DooM style, just bright-to-dark with no extras on the end...

update XPM icon

See merge request STJr/SRB2!267

Change default sound volume

See merge request STJr/SRB2!238

SDL Mixer fixes

Closes #31

See merge request STJr/SRB2!260

Fix white being treated as transparent.

See merge request !266

Woops! All trans

See merge request !265