Bug fix merge

As per usual, this pull request contains all my previous stuff, but it should get the Master up and running again (we built upon my previous work, since we knew that works). The Stokes' Sphere test case still fails, but I leave that up to Stefan to check thoroughly. In this pull request we removed the problems with the compiling (that came up today) and an error that was in the boundaries for the GPU LB (the first boundary was not set, also an error that came into existence as of the latest updates to the master). 

Please merge!

Joost