Added Rectangle functionality

Added the ability to calculate the aspect ratio and center position, as
well as centering to a point, and fitting inside/outside another
rectangle
calculate -> get and returns
Forgot to change centerTo->setCenter and more chains
Merge pull request #525 from JonECG/rectangle

Added Rectangle functionality
Fixed a very important typo.

Somebody Ctrl-C'd + Ctrl-V'd.

time for a `git blame` :D
Fixed my typo trying to fix a typo

I am not a smart man.
Merge pull request #528 from sinistersnare/master

Fixed a very important typo.
Merge pull request #529 from xoppa/master

Model/Mesh builder small changes
Dont use iterator, meshpart.equals and untransformed node bounds