fixes problem with dpcg_precon.cpp where multiple DPCG solvers are called. no deg faults now and cuda-memcheck also works. Tested for bubbly flow 128 9bub
these two filles may not be needed but i am not sure of them so added.
changed stopping criteria in cg files to one that uses norm of rhs as iteration control criteria. removed cal of levelset prep time from examples/dpcg.cpp
dpcg_for_dg works for p3_n20. also with IC(0) preconditioner for the inner solve.