move to actual priority queue. manage queue via thread pool and single polling thread to avoid race conditions via reading. remove activity abstraction because probably not needed. modify UnitCreationOrder to show how new stuff might be used instead
Merge https://github.com/omsmith/rts_server

Conflicts:
	src/server_battle/UnitCreationOrder.java
Owen's commit

Going to figure out what this means for all the related systems
tomorrow. Lots of re-codeing ahead