- Added gui component base method: update.
- gui window now checks if mouse is on top of titlebar.
- Added layout update method as well, obv.
- Gui surface colour will be based on a 'type' index that will be passed and switched in the fragment shader. So far, it does not work for some reason, it just catches ONE of the (hopefully many) indexes (0, just 0. It ignores any other number). TODO: find out wtf is going on.