Updates, extensions and comments for Vector2,Color,Point and Rectangle

Changes :
Vector2 :
	now fully commented,
	all things sorted within the regions,
	added ToPoint method,
	added missed overloads from XNA, for Transform and TransformNormal
Color:
	some comments changed,
	all things sorted within the regions,
	added Invert static method,
	increase performance for == and != operators,
	some cleanup	
Point:
	some comments changed,
	increase performance for all operators
Rectangle:
	few comments changed,
	ToVector4 added