EGU 2021: split the workflow and run it on large datsets

[fnattino]

• [x] Collect and retile the Arctic DEM
• [ ] Collect and retile the Copernicus DEM
• [x] Rasterize the Randolph Glacier inventory
• [x] Rasterize the coastline shape file
• [x] Generate enhanced shadow images and shadow-connectivity lines
• [ ] Coregister scenes using the shading image generated from DEM
• [ ] Extract elevation differences from shadow-enhanced images, connectivity lines and coregistration