Edit ids. Change implementation of logic_player

* Now army and building are Hashtables in logicplayer
* 2 new method in order to get a unit by its id (same for building)
* change some stuff related to ids
Merge branch 'master' into hashplayer

Conflicts:
	src/engine/Game_engine.ml
Merge pull request #120 from GL-MPRI-2014/hashplayer

Hashplayer