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
Don't allow null selected nodes.
AssetLoader changed to receive the resolved FileHandle along with the file name.

See comments in #517.
Sync GWT emulation with changes in f3b2d34
Added bleed setting to fix linear filtering with non-premultiplied alpha. Removed duplicate padding setting.
Merge branch 'origin/master'
AssetLoader changes.
returns the matrix4 from lerp() to allow chaining
Merge pull request #527 from g-pechorin/patch-1

returns the matrix4 from lerp() to allow chaining
Model/Mesh builder small changes
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
Avoid flush if blending doesn't need to be changed.
Improved native library extraction and loading.

I've found a small percentage of users can't write to the temp directory. Eg:
https://code.google.com/p/libgdx/issues/detail?id=1504
These changes improve the chances of being able to extract and load a library. For load(), multiple locations are tried to extract and load the library. For extractFile(), multiple locations are tried to extract the file.
Merge branch 'origin/master'