Make MULTREGT work for NNC.

The region multipliers are no longer added  to the cartesian logical
MULT[XYZ] structure. Instead a new method
getRegionMultiplier(globalIndex1, globalIndex2,FaceDir) is added that
return the multiplier between globalIndex1 cell and globalIndex2 cell.
The face direction is added to support directional dependent MULTREGT
input. This implementation of MULTREGT also supports restricting the
multipliers to only apply for NNC or NONNNC.
address the review comment of #373
Merge pull request #380 from andlaus/multregt

Multregt