GIS raster utility methods

gis_utils.spread2d(obs[, msk, nodata, frc, ...])	Returns filled array with nearest observations, origin cells and friction distance to origin.
gis_utils.get_edge(a[, structure])	Get edge of valid cells.
gis_utils.reggrid_area(lats, lons)	returns a the cell area for a regular grid with cell centres lats & lons [m2].