Exercise solution for DEM pipeline

1. Modified pipeline to do hillshaded before hypsometric rendering

$ gdal raster pipeline \
    read dem.tif ! \
    hillshade ! \
    blend --input [ read dem.tif ! color-map --color-map test.cpt ] --overlay _PIPE_ --operator hsv-value ! \
    write out.tif --overwrite

2. Generate colorized and hillshaded maps as intermediate results

$ gdal raster pipeline \
    read dem.tif ! \
    color-map --color-map test.cpt ! \
    tee [ write dem_colorized_tee.tif ] ! \
    blend [ read dem.tif ! hillshade ! tee [ write dem_hillshade.tif --overwrite ] ] --operator hsv-value ! \
    write out.tif --overwrite