Carcode GUI

At the beginning of the project I wanted to use PGU library to create a nice GUI for carcode, however, after moving to OpenGL it seems that pygame refuses to blit to screen surface when OpenGL is enabled, thus I had two options, look for a workaround and use PGU or to use an library which renders with OpenGL.

A workaround may implicate disabling OpenGL support from surface after arena drawing code, looking around it seems that the problem is with SDL and thus a workaround is discarted, it may be worth but it can be too much effort and time, it will complicate distrubution too. Anyways, PGU hasn't been updated since 2007, go figure.

Looking for an OpenGL compatible library doesn't gives much hope, there is a couple that may do but that would be another dependency, I will keep checking if I find something useful.

Meanwhile I created a branch to work on create a set of GUI widgets for carcode, is not that difficult and we don't need them to be very complex, currently I have labels (text), buttons, lists (listbox) and text inputs (simple one line inputs) working and integrated with carcode all this using OpenGL.

Additionally I'm looking at Box2D, a 2D physics library which has python bindings, I will create a branch to play with it later probably after GSOC is over.

When the project is more or less featureful I will start working with performance, there are many places where I can improve, specially OpenGL rendering code which has many optimizations available.