Started adding an OpenGL based UI module.
Corrected Pi value
Updated the OpenGL UI to map arena pixels to OpenGL pixels 1-to-1 simplifying the implementation.
Also added another simple bot and an OpenGL debug helper function.
Cleaned up exports and added some comments.
Removed unused imports.
Removed unused dependencies from the cabal file.
Merge branch 'master' into OpenGL

Conflicts:
	LambdaWars.cabal
Fixed a bug in arena generation causing generated bots to be colliding.
Added support for textures to the OpenGL UI. Now the bots are pretty.
Clened up redundant code.
Bot bot collision test was returning the inverse of what it should be.
Bot bot collision test was returning the inverse of what it should be.
Changed the way bullets are fired so what new bullets start on the edge of the bots firing them rather then in the centre.
Changed the way new bot states are generated so the direction of the turret and radar are unit vectors.
Added a simple bot that just fires, useful for debugging bullet computations.
Merge branch 'master' into OpenGL

Conflicts:
	examples/SimpleBots.hs
	src/Engine.hs
	src/GeometryUtils.hs
	src/Main.hs
Explicitly set background colour of the battlefield and fixed a merge issue.
Added bullet hit testing.
Added wall collision testing.
Added bot naming and the UI data type for abstracting away the UI that's being used.
Added automatic frame refresh to the OpenGL UI and fixed a couple of bugs introduced by naming bots.
Changed the UI type to return () to make it fit with OpenGL and added some comments.