Got rid of a lot of superfluous checks in dslash_quda.cu
Fixed the flops count for staggered dslash

In particular, I now get the correct count if I
switch off communication.
Added output to each of the staggered preconditioning inverters
Added flops count to inv_prec_cg_quda.cpp
Added ordinary CG as a special case of preconditioned CG (again).