Handle all relations with from, via, and to members in the same manner as turn restrictions.

[BjornRasmussen]

There are quite a few different relation types that can currently be broken by id with the "split way" functionality. These include:

1. Manoeuvre relations
2. turnlanes:turns
3. Connectivity relations - Proposal page
   ... and possibly others as well.
   All relations with this format should be handled identically by the split way tool. I suggest modifying the code to improve the relation (remove duplicate from/to way) if the relation has from, via, and to members.
   The current design, which I think already has this capability for turn restrictions, should no longer look for the tag type=restriction and instead look for has from, via and to members.

[bhousel]

Seems reasonable 👍