WIP: Kart net improvements port

Ports Kart net improvements, notably netticbuffer and antifreeze. They fix weird netgame framerate caps due to lag as well as freezing when players join / time out.

This is a raw port and so far it doesn't work (breaks joining, hence WIP tag), but making this Merge Request should make it easier to compare the diffs to see what went wrong to fix it later down the line