Fixed ButtonGroup not removing from the checked buttons list.
Keep names for drawables to make debugging easier.
Make Button use padding of all drawables, not just the first.

#2322
Merge remote-tracking branch 'origin/master'
Have Button update background in setStyle.

closes #2322
Fixed copying TintedDrawable.
Chachachachanges
SelectBox, configurable show and hide actions.
Add isCatchBackKey to Input interface
Added getLevel and getIndentationSpacing.
Javadocs.
Merge remote-tracking branch 'origin/master'
Javadocs.

#2326
Bugfix for Viewport.getPickRay
Merge pull request #2327 from nooone/viewportpickray

Bugfix for Viewport.getPickRay
Vector3#toString to match Vector2.
SelectBox refactoring.

* Now fires change events correctly.
* Moved select box list functionality to SelectBoxList, code clean up.
* Better way of hiding select box list, list being open doesn't stop input events elsewhere.
* List reverts to selected item on mouse exit.
Merge remote-tracking branch 'origin/master'
Javadoc.
Add TextureRegion support to TextureAttribute, see #2321