Ordering the trails by length (either routed or given)

[lemio]

Issue:
When zooming out to get a better overview of the currently existing routes; the routes shown are 'polluted' by the alphabetical ordering.

Ordering could also happen by how important this route is, for example how much km of the route is present in the current view, or simpler, how much km is the total length of the track... (either mapped or reported). This would also be great data to have in the list (shown in the front end and shared through the API) with items to get a better overview.

This problem is specifically present for hiking (since the data is polluted, some smaller routes are marked as continental)

For cycling it is not as bad as for walking, since most are EuroVelo and there is not that much routes that start with letters before in the alphabet.

[lonvia]

I'd rather recommend to fix the classification of routes.