Updated cub to version 1.3.1 for multi-dimensional block reductions.
Fixed bug when copying between different gpu colorspinor fields in different gamma bases.
Fixed bug in FloatN index helper function in colorspinor::FieldOrder.
Rewrite of transfer operators to remove temporary intermediate.
Added hooks for setting GPU prolongation and number of mg levels through the command line (only enabled for prolongation.
Merge branch 'multigrid' of https://github.com/lattice/quda into multigrid