* [chore] Migrate accounts to new table, relax uniqueness constraint of actor url and collections
* fiddle with it! (that's what she said)
* remove unused cache fields
* sillyness
* fix tiny whoopsie
* [feature] User sign-up form and admin notifs
* add chosen + filtered languages to migration
* remove stray comment
* chosen languages schmosen schmanguages
* proper error on local account missing
* [feature] Account alias / move API + db models
* go fmt
* fix little cherry-pick issues
* update error checking, formatting
* add and use new util functions to simplify alias logic
tobi