Disable the fixed function (non-shader) path.

# Description:
Disable the non-shader path. 
Works on the Intel 4000 gpu I've got ;)

This is so that if we get the nod from the [dev](http://pioneerspacesim.net/forum/viewtopic.php?f=3&t=74&sid=415feeb6d37954c68c8fe14d35a9e500) or [SSC](http://spacesimcentral.com/ssc/topic/4035-is-it-time-to-start-requiring-shaders/) then we can just merge it in.

This leaves the RendererLegacy code in there, it just disables it being used and changes the graphics startup check to fail if the players GPU doesn't support OpenGL 2.0 or greater.