Use Alchemy SSAO
Use dFdX/dFdY to compute normals in SSAO.
Allow depth test on debug physic view
Use the mipmap trick to speed up ssao.
Improve SSAO perf
Tweak SSAO params.
Remove ssao depth guard.
Merge branch 'SAO'
Render SSAO at fullscreen resolution.
Merge branch 'master' of https://github.com/supertuxkart/stk-code into random-gp