put median buffer on stack
Merge remote-tracking branch 'upstream/edge' into upstreamedge
Merge pull request #570 from wolfmanjm/upstreamedge

refactor median buffer
Merge remote-tracking branch 'upstream/edge' into grid25level
Save and check number of grid points in a ZGrid file to ensure the grid
is not corrupted

Ensure the compensation transform is disabled during running of the grid