batch commit:
	changed interface Algorithm into an abstract class
	CSP: commented out some prints, improved toString() & added a couple of getters & tests
	Constraint: added a few getters + added concerns method & test
	Backtrack: commented out prints + fleshed out start()
	Variable: generated hashCode & equals	+ added some doc
started writing Arc Consistency Algorithm:
	expanded IntegerDomain's capabilities & associated tests
	created Arc class
	started implementing AC1 + tests