Warn about keys representing quantities when splitting a way

[Zverikk]

Some parking lanes have been mapped with capacity specified, in tags "parking:lane:<left/right/both>:capacity[:disabled]". When splitting such way, the capacity tag is duplicated on each part of the way.

Could you please make a warning after splitting a non-closed way with parking lane capacity specified?

[skyper]

In general, we need a warning when modifying the geometry of an object with keys defining a quantity, like *capacity*, *quantity*, *duration*, *volume* distance and some more specific ones like step_count. The tag conflict management (combining ways/merge nodes) already handles some of these tags.

Split way should also warn with these keys.
Some examples:

• a non-closed way highway=* + parking:lane:right=parallel + parking:lane:right:capacity=10
• a non-closed way highway=steps + step_count=12
• a non-closed way route=ferry + duration=10:00
  • should offer to create a relation
• a closed way amenity=restaurant + capacity=50

Not sure how to proper handle relations with these keys, like multipolygon instead of closed way and splitting a route to make a superroute.