Hole punching backport

See merge request KartKrew/Kart!445

[1.4 ver.] Da anti-grief stuff

See merge request KartKrew/Kart!474

* Do not allow any joining spectators if anybody got onto the last lap while not in FREE PLAY (this is the same condition as nospectategrief, for consistency).
* Reset nospectategrief to 0 if there is literally nobody playing, to prevent a fully locked-out server.
* This means it's not a problem to reset spectatorreentry even with the map command.
* Change the default for spectatorreentry to 30 seconds, from 60.

Fix for beocming a spectator while an SPB is on your trail having it continue to follow you around. Done here because it's related to spectators messing up other people's fun.

Disable the "%s became a spectator" message if you haven't actually entered the game, to prevent an avenue for spam.

Merge branch 'spectator-little-things' of https://git.do.srb2.org/KartKrew/Kart-Public.git into public_speclil

# Conflicts:
#	src/f_finale.c

Credits changes for 1.4

See merge request KartKrew/Kart!469

Add Opulence objects

See merge request KartKrew/Kart!442

Delayable linedefs crash fix

See merge request KartKrew/Kart-Public!269

Error checking for running out of freeslots

See merge request KartKrew/Kart-Public!267

Uses loop variable to determine error condition
Also small change to lib_freeslot for SFX for consistent use of I_Error

Add my full name in the credits

See merge request KartKrew/Kart-Public!264

Instashield crash fix

See merge request KartKrew/Kart-Public!260

Small mapobjectscale fixes

See merge request KartKrew/Kart-Public!259