0.13.0

Fix measure being 32 units inaccurate.
Fix landing velocity being measured 1 tick early.
Using the !menu command now prints a message to chat again.
Added kz_player_model_alpha cvar which controls player model transparency.
Added kz_chat_prefix cvar which controls the prefix used in chat messages.
Fixed TP menu not updating when starting timer, checkpointing, teleporting etc.
Fixed timer text flashing rather obnoxiously.
Fixed info panel drawing if only speed is enabled and you are paused.
Rejoining from spectators and spawning in now resumes you.
Some minor optimisations and fixes.