Revert "Merge master"

This reverts commit a695c197b2915e4082fe8d12da445541c4b8f167, reversing
changes made to b2a563c746bcccc688ad83b2159d6a79c379a847.
Bugfix: A new local only user was now able to change the online account.
If a new account is created with an online account, make the online account
the default.
Reenable shadows for instanced mesh
Put RSM draw in its own method.
Add support for instanced normal map mesh.
Add Debug for instanced vertex type mismatch.
Exit cmake with error if xrandr library was not found.
Port UI shaders.
Port particle rendering shaders too.
Extract ParticleVBO from gpuparticle.cpp
Bring back the rain
Merge branch 'master' of https://github.com/supertuxkart/stk-code
Factorize some GL code in gpuparticle.
Factorize again code in gpuparticle.
Clean quaternionbuffer at the right place.
Factorise attribute location of simulation program.
Port simple simulation particle shader.
Port heightmap simulation shader.
Factorise simulation code.
Fix malloc/delete mismatch