Implement an initial practice mode. Closes #107
Map loading commands are slightly smarter.
Fix NPE for splash potions in non-match worlds.
Fix NPE in BlockFromToEvent's handler
Refactor spectator-specific events into SpectatorListener
Add sensible static from*() API for a few enums
Implement basic player-cycling (untested). Closes #103

* Use feather to cycle via item use (L = backward, R = forward)
* Adds "/autoref cycle [-n] [-p]", no option defaults to forward
Clean up NPE in playerInteract and playerEntityInteract
Remove restriction on kill registration. Addresses #119
Update colors.csv, as well as add color generation script
Make use of AutoRefTeam.getTeamGoals(Class) more.
Track furthest accurate bow shot. Closes #64