GUI plays nicely (more or less) with the API

Only material API change is to how Game.nextTurn works, now
takes a candidate coordinate pair as input and
returns false if the turn fails.

TODO: Look for bugs in the game if turns fail,
not sure what the game state looks like after
that.
Folder restructure, dialog box addition
Interim, not fully functional
Merge branch 'ui_progress'

Conflicts:
	polar/game/Game.java
	polar/game/Move.java
	polar/game/Play.java
	polar/game/Player.java
	polar/game/start.java
README Merge