Keep lemma translation for every form

Closes #478

This was not a bug per se - in fact it did exactly what I wanted it to
do, but probably under a false assumption. Every form stored their own
lemma translation, but as there is no visual link between them, this
appears to be counterintuitive.


Also triggers the need for a save when this field is updated and adds translations for its label.

TODO: Really add the translations...