Compute half transmissibilities based on local coordinate system

hTrans(cellFaceIdx) = K(cellNo,j) * sum( C(:,i) .* N(:,j), 2) /
sum(C.*C, 2),
Only for diagonal tensors, off-diagonal permeability values are ignored
without warning
Implement comments for PR#249
1) Add the possibility for the user to chose between local and global
coordinate permeability in the transmissibility calculations.
2) Trow for CpGrid
3) Add default for switch
Implement code style comments
Merge pull request #249 from totto82/locTrans

Compute half transmissibilities based on local coordinate system