Allow custom values for preset tags

[irismessage]

Recently I've been tagging waste bins and in my country the waste type is generally not just one type but some combination of litter, dog_excrement, and cigarettes.

I couldn't find a way to enter custom text in the waste= tag, so I wasn't able to tag these. Making the waste= preset a multi select would also fix the problem, but I could see custom values being useful in other similar situations. That way I could enter waste=litter,dog_excrement for example, and save it for easy recall

[irismessage]

just remembered the other thing, I couldn't tag sport=chess on a picnic table

[irismessage]

I figured out how to tag the chess table, there's just a top-level preset for that