[Feature proposal] Option to change renderer from Game UI

[runlevel5]

I would like to propose a new option called Renderer which would be available through Setup > System > Graphic menu.

Please see mockup video:

https://youtu.be/0LdDNXddz1Y

[NuclearMonster]

That would be good, we also have #842 to deal with for thinking about this, but at least on a first launch of ioquake3 with our modified pk3 it would let you choose a renderer.

[runlevel5]

@NuclearMonster I can tackle this feature once #861 is in