Fixed up the FlxShapes

Fixed a lot of inconsistency in the FlxShapes. Now the following should be true:

* Width/Height of shapes reflects underlying geometric boundaries (ignores stroke)
* Offset should be automatically set so that object's x/y matches expected position
   * X/Y = upper-left
   * Turn on debug lines, boundaries should be in the middle of the stroke (for a rectangle), etc.
I don't see anything in the haxe manual about Enums and strings, can you explain how they can be converted back and forth? 
http://haxe.org/manual/types-enum-instance.html

(That would be very handy if it's true)