Anti-Crash (Performance Booster)

Fixed:

1. Rare sv_globalcleanup attempt to index a nil value error

Improved:

1. Netrate limiter functionality
2. Should fix some conflicts with mods that use poor net code
3. Tighter limitations for net spammers

New:

1. Large contraptions undo/removal lag fix
2. Completely removes the server lag created when the engine tries to remove many entities with tons of constraints
3. This fix is global, including the anti-crash commands and the default spawn menu admin buttons