fixed bug for asmmetric preconditioning for non-degenerate twisted mass, optimized constants initialization
a few corrections in dirac_twisted_mass.cpp file
Major rewrite of comms interface (closes #46)
More comms cleanup.  Everything that works with MPI should now also
work with QMP (HISQ forces, link-fattening, etc.)
Fixed memory leak in multi-shift CG.
Fixed race condition for T-dimension multi-GPU communications that was introduced with merged packing kernels.
Added check that src and dst fields with the same precision must have the same byte size.
Fixed incorrect odd pointer references that occur when using full fields when the ALIGNMENT_ADJUST macro changes the size of allocated memory.
Added missing epsilon to quda_fortran.h needed since Non-deg twisted mass merge.
Merge branch 'master' into multigrid