Cleaned up guards and made it pass all the lb_gpu testcases, with the exception of object_in_fluid.
Started implementing the lbnode_set_u infrastructure for the GPU LB in a way that is equivalent to the CPU.
Merge remote-tracking branch 'georg/Merged_EK' into Merged_EK

"Only the object_in_fluid_gpu testcase does not work."
Worked on object-in-fluid problem, not fixed yet, however.