Digiku said they'd handle the new button defaults so \m/

Needs the config default-changing shenanigans done still, not sure how to tackle that yet. Now the game is TOTALLY playable from a fresh install if you just plug in a controller.

Apply srb2home path to EXEC, SAVECONFIG, and debugfile

See merge request STJr/SRB2!379

Awayviewmobj sanity checks

See merge request STJr/SRB2!377

Fix savegamename being improperly built

See merge request STJr/SRB2!378

Add some checks to prevent invalid awayviewmobjs from crashing the game. Not fullproof but at the least the P_CameraThinker crash no longer happens

Remove windows installer

See merge request STJr/SRB2!372

Update code versions to 2.1.21

See merge request STJr/SRB2!338

Block previous versions' config defaults with EXECVERSION consvar

See merge request STJr/SRB2!371

* Change alwaysfreelook2 to be consistent with alwaysfreelook (the only one that wasn't the same)

Controller defaults: Set Ring Toss to right trigger instead of left trigger

See merge request STJr/SRB2!370

Change 2p controller defaults

See merge request STJr/SRB2!369

Add OS and 32/64-bitness to VERSION console command

See merge request STJr/SRB2!368

Fix 64-bit build-using admins not being able to kick players besides themselves, by not checking sendingsavegame[] code at all if not the server

it turns out playernode[pn] is typically 255 in the above situation, so sendingsavegame[playernode[pn]] goes out of bounds ...but goodness knows why 32-bit builds didn't suffer the same bug, seems to have been pure luck

It turns out the game was sending the full size of the motd buffer (254) rather than just the size of the string made, therefore sending a load of garbage and making the game apparently execute unknown or illegal net commands

Fix the game being basically broken due to multi-admin, by porting over some missing changes from Kart