Save item cooldown states

[Exterminate5573]

Closes #730

[CLAassistant]

All committers have signed the CLA.

[ThatGravyBoat]

It may be worth renaming cooldown groups to just cooldowns and set item cooldowns to just set cooldowns to keep it consistent

[mworzala]

Currently gives an NPE when verifying an empty map

Caused by: java.lang.NullPointerException: Cannot invoke "net.hollowcube.mapmaker.runtime.PlayState.cooldownGroups()" because the return value of "net.hollowcube.mapmaker.runtime.PlayState.lastState()" is null
	at net.hollowcube.mapmaker.runtime.parkour.ParkourState$AnyPlaying.resetPlayer(ParkourState.java:152)
	at net.hollowcube.mapmaker.runtime.parkour.ParkourState$Playing2.resetPlayer(ParkourState.java:230)
	at net.hollowcube.mapmaker.runtime.parkour.ParkourState$Playing2.resetPlayer(ParkourState.java:197)
	at net.hollowcube.mapmaker.map.AbstractMapWorld.safePointTick(AbstractMapWorld.java:321)
	at net.hollowcube.mapmaker.map.AbstractMultiMapServer.safePointTick(AbstractMultiMapServer.java:399)
	... 12 common frames omitted