This is an addition to the Button control. It adds a possibility to add an image.
It currently supports text Over, Above or Below he image. Left/Right still have to be implemented. Layout can be changed at runtime.
Currently, with above or below layouts, the elements (image/text) are vertically constrained top or bottom, which make them
appear at the very edge of the button, with a possible empty space in the middle if the image is wider than taller.
This could be avoided by using more panels to layout the elements and/or calulating the whole layout in the controller and/or allowing changing childLayout add runtime. I don't know which option would be the best.
I added an example to nifty-examples, although it was more useful for testing than it might be to users.
Buttons without images still work correctly.
The patches are against recent git master branch.