[Feature] New text edit control

[inmarket]

There is now a new gwin textedit widget.

It works with both real keyboards and the virtual gwin keyboard.

A new demo in demos/modules/gwin/textedit has been written to demonstrate this.

All other gwin widgets now have the capability to accept keyboard input although the textedit widget is the only widget that currently implements this.

As a result of the new capabilities a new style color element has been added for the focus rectangle. If you statically initialize your style color set you will need to add the new element.