Menu System

I added a simple menu system with buttons that respond to hovering and clicking. 

I also added a plethora of different powerpoint-esque transitions (is that a word?), which will allow me to seamlessly transition between the menu and board without having a jarring cut. You can press "m" to sample one of my transitions.

You can navigate between the different screens, but that's pretty much it.

Currently, you can only play standard chess under the "Play" section. Every other game mode is still in development.