Please look at the merge request description for a full explanation, since I know the vanilla team has been hashing this out and I don't want to add fuel to the fire without at least presenting a solid case.

Create G_FreeGhosts, for the benefit of G_DeferedInitNew (assuming it actually needs to do `ghosts = NULL;` at all)

(oddly enough, this actually revealed some secret file dependencies previously included via r_things.h! I also needed to include d_player.h in r_skins.h itself it seems)

It makes more sense for 100% deadzone to just make it so that
you have to push the axis all the way to trigger it,
rather than 100% deadzone resulting in no axis input
ever happening... So, let's make it be the former way instead

Fix division-by-0 crash with gamepad deadzones
The problem was that it checked if A was more than B,
then lowered A to a max value, then subtracted B from A,
then divided something by that, without checking if A minus B was 0,
allowing division by 0 if B was the same as that max value

This fixes that by making sure that A is less than the max value

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.

This fixes player 2 using player 1's "cam_turnmultiplier"
instead of player 2's "cam2_turnmultiplier"

In splitscreen stuff, player 2's "cam2_turnmultiplier" implementation
was wrong compared to player 1's "cam_turnmultiplier"
This commit makes player 2's multiplier work just like player 1's does

This reverts commit a00dfcf4.

Analog + no directionchar is old analog (now known as
CS_LMAOGALOG because lmao if you still use it).