Added Laggy Collision Gravity

The Blocks fall and stop when they hit a solid block. Also added right
mouse button to add a solid block. But right now the method is very
laggy.
Fixed Some Things
Reversed Mouse Buttons

Switched the button functions of the left and right mouse buttons.
Fullscreen and Esc to exit
Finishing Touches on Gravity

And a little bit of player
Another Change
Another Change
Lots of Stuff

Sort of finished player class. Fixed some issues. Added item class.
WorldGen