Consolidate tags before saving

[tordans]

I don't consider this urgent but lets have a ticket regardless:

Its possible to create tagging like this:

parking:lane:both	separate
parking:lane:left	separate
parking:lane:right	separate

https://www.openstreetmap.org/way/168945516

I thinks this was both=parallel, then I changed left, right to separate and maybe also both (cannot remember).

In any case, before saving the editor could consolidate the tags and favor either the both or separate tagging.