when user selects a parser, it may auto-select the vendor, but keeping
that all in sync is complicated. this seems to be an improvement but
it could likely use more..
- invoke vendor handler where appropriate, e.g. for parsers
- reverse "polarity" of dropdown chooser setting; rename it
- tweak autocomplete behavior yet again, for dynamic values
- auto-select vendor upon parser selection, when possible
these changes are all with Buefy "forms" support in mind. hopefully didn't
break any legacy/jquery stuff... and yeah, lots more left to do still for the
sake of Buefy forms
