This is accomplished by simply preserving
the player's body after disconnecting.

Bodies will despawn after the number of minutes
specified by the "rejointimeout" console variable (float).
A value of 0 disables the feature completely.

Clients rejoining are identified by their IP address,
and may rejoin even if the server is full or joins are disabled,
for as long as their body remains.

From a technical standpoint, when the user disconnects,
the player they were controlling does not leave,
the underlying player_t just keeps working normally,
except it does not receive any input anymore.
When the user reconnects, they are simply "relinked"
to their player_t.

Those "soulless" players can be identified through
their "quittime" field, which is the number of tics
elapsed since the user disconnected, or zero
if still connected. "quittime" is exposed to Lua.

I think this gives extra indication that abilities face toward
the camera now.

(cherry picked from commit 17bdf39dc8372ed9c6c31fa8d00eba03396a55bf)

This is a huge hack as it requires another font set, with each character's offset manually being set using SLADE.

This reverts commit 749c2753.

Also:
* SPR2_XTRA - instead of defining lumpnames in S_SKIN, those kinds of assets can just be bundled into the spriteset. Required for ending cutscene stuff, I guess, but also done for HUD life icon and character select image (aside from Sonic&Tails, still SOC'd in).
* Minor oversights in SPR2 support corrected.
* Better evaluation, featuring ending assets.
* Intro has warping-in blackrock, reusing ending assets.
* Cutscene text now supports lowercase (intro and custom).
* Disable the asset-fucking "gamma correction" I put in over two years ago when implementing colour cube. (This is the only thing I could move into another branch if you MUST, but it's basically invisble in the diff so w/e.)
* Don't blank the screen if the top left pixel of a screen-covering patch is transparent. (Checked via nonzero topdelta for first column)

Bugs:
* OPENGL ONLY: The first ~20 frames of both endings are fucked. A little help here? Might be HWR_DrawFadeFill's fault, which I just created. OR it could be in f_finale, but I doubt it, since it doesn't appear in Software.

* Re-fix chat HUD position, and make it not move in match (which it needed to do in 2.1).
* Fix HU_drawPing for the new palette.
* Change the condition for greying out players, since the current one was buggy.
* Allow for tokens on the coop MP HUD, and use the small emeralds so there's space for them.
* Fix the mapping between skincolours and name colours in new chat, specifically to take into account every possible text colour (as opposed to the port previously done, which only used the 2.1 text colours and looked like ass as a result).