Fix some compiler warnings

See merge request STJr/SRB2!1504

Check against null tmpusher source before attempting to push a thing.

See merge request !1413

tRNS chunk fix

See merge request STJr/SRB2!1393

Optimize Picture_GetPatchPixel

See merge request !1342

Remove music slot compatibility

See merge request STJr/SRB2!1321

Scale minimum dashmode thok speed on actionspd, not normalspeed

See merge request !1311

Set the target of a spawned ghost to where it came from.

Closes #517

See merge request !1358

Make steam apply sprung flag

See merge request !1365

Don't apply pw_justlaunched if the player didn't actually launch off a slope

See merge request !1447

No fire shield palflash (resolves #512)

Closes #512

See merge request !1473

Change Raspberry's chat colormap to V_ROSYMAP

See merge request !1441

Add more actions for slope copying

See merge request !1406

Add linedef specials for multitagging in binary maps

See merge request !1485

The year is 2021

See merge request !1500

Some of these integers exceed the precision of float. In
that case the number is rounded. The rounding shouldn't
matter too much anyway, so just shut the compiler up.

Fix a series of buffer overflows in SOC (primarily Character section) loading

See merge request !1457

arccosine Lua exposure

See merge request !1455

[SUGOI] Allow setting sound captions in SOC

See merge request !1469

Monster cleaning up again

See merge request !1433

Load netgame error fixes

See merge request !1482

Polyobject over 3D floor fix for software renderer

See merge request !1488

2.2.9 prep

See merge request STJr/SRB2!1499

Stop using metatables with light userdata

See merge request STJr/SRB2!1495

Update URL on the addon screen

See merge request STJr/SRB2!1489

Fix MusicChange hook not returning some values correctly

See merge request STJr/SRB2!1496

See 7df6a309 and 83a87042. I didn't realize that light
userdata's metatable is shared--like numbers or strings.
So it cannot be paired with a metatable.

I also made a few minor tweaks to Lua cvars, other than
accounting for the double pointer in the userdata.

This reverts commit d4c08a84, reversing
changes made to e100f21d.