Originally 6acd99c0

The config file is starting to get close to the old max,
so this should be enough headroom for a while...

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.

(Looks at 4865a190...)

(cherry picked from commit 0e9d69d6a3759686ca8bb567817be650291ea0e1)

Co-Authored-By: Jaime Passos <jimita@users.noreply.github.com>

Ported from Kart, original commit also by me (toaster).

* Fix cv_pointlimit's weird behaviour in match mode by standardising the switching between "named" and "range" values in CV_AddValue.
* Optimise M_ChangeCvar.

Kart-port round 3, with the original commit written by me, toaster.

Detect infinite alias self-recursion mixed with other commands, such as in the case of `alias a "echo test; a"; a`.

(Unfortunately, this does not work if "wait" is used instead of "echo", but oh well)