Automated detection of undivided glaciers #44

Based on simple heuristics and OGGM's flowline algorithm, it should be possible to develop a tool able to detect glaciers that need to be divided.

For example:

• is the max elevation of a glacier on the outline of far into the geometry?
• do the centerlines have to up glacier?
• etc.

Having a flag in the RGI tagging potentially "undivided" geometries would be quite useful...