IGUI : a minimalistic immediate gui for jme

This is mostly a wrapper around Picture and BitmapText.
For people that just want to show some images and text on the screen without all the fancy stuff.

No objects references to keep around (besides the main igui instance obv) . Things are just rendered 1 frame (unless defined with the persistent flag) and then discarded. The next frame the whole gui has to be rebuilt with updated informations.The methods can be called anywhere in the update loop.