Improve multi-gpx management for route creation/restructuration

[StC-OSM]

GPX mode is a great solution when creating a missing route in OSM. And multi-gpx looks like it has great potential to make large routes more manageable in GPX mode.

However, when you combine the two situations above there currently are serious issues: as soon as you change the structure of your (new or refurbished) route, you need to destroy and recreate the multi-gpx monitor... and re-upload all gpx segments one by one (all 65 or 120 of them...)

I am not clear what the solution should be. Just some thoughts:

• it would we great if uploading a gpx file that contains multiple segments could automatically produce the segmentation
• and it would also be great if any change of structure of the OSM route also triggered a restructuring of the monitor
• but of course, the whole problem would be to determine what can be mapped on what, what the missing segments are, etc.