Fix to error in 1.2 spotted by Carolin Stang (as listed in issues) - 1.1
and 1.2 producing different results. This was due to a change in the
SpatialGrid method, and as such this has been returned to the method
used in 1.1. 1.2 now produces results that equal that in 1.1. However
the 2D padding has been reintroduced into 1.2, as it was in 1.1. This
obviously needs more examination, and will be addressed in due course
Merge pull request #22 from kalden/1pt2_Fix

Fix to error in 1.2 spotted by Carolin Stang (as listed in issues) - 1.1