Added the fourth order routines in the thermo_buoy
Save the CUDA settings properly to the CMakeCache file so that changes can be edited
Use tmp1 and tmp2 instead of tmp2 and tmp3 to be able to eliminate tmp3 and tmp4 from the GPU. This frees enough memory for a 512^3 case.
Cleaned up the timeloop
Merge branch 'cudaupstream' into bigmerge

Conflicts:
	src/timeloop.cxx
Merge remote-tracking branch 'origin/cuda' into cuda