Some support for non-yes/no multicombo fields

[bhousel]

Most of the multiCombo fields supported by iD are 'yes'/'no' only.

recycling:whatever = yes/no wiki
fuel:whatever = yes/no wiki
monitoring:whatever = yes/no wiki

But for some of them, people have decided that they want to put other values in there:
payment:whatever = yes/no/interval wiki

The new language field needed for #5261 works like this too:
language:whatever = yes/no/main wiki

Previously I was lazy and just ignored all the non-'yes' values. Going forward, iD will treat anything non-'no' as if the value is set, and make sure not to overwrite it's special value with a 'yes' if the user tries to re-add it again in the multiselect field.