OSK overhaul: Adjust button functionality, and some text positioning.

This pullrq makes the OSK much, much more convenient to use in the following ways:
* Makes select function as a real shift button(meaning it swaps upper/lowercase)
* Makes the R trigger cycle forward through all available keyboard languages
* Makes the L trigger cycle backward through all available keyboard languages
* Moves text around so it looks better
* Makes tasks like https://github.com/hrydgard/ppsspp/issues/3915 far easier(via the select button functionality change)

![Screenshot 01](http://i.minus.com/ibiIh99KnmGQy3.jpg)