Hillshade with rastertools : spatial resolution fix

fixing hillshade rastertools spatial resolution

Closes #119 (closed)

changed milestone to %1.11.0

requested review from @guillaumeeb

assigned to @micherbl

Just a little note for the future: it works because the DEM is already reprojected to the correct target spatial resolution, so fine by me!

mentioned in commit fefcc758

merged