WIP Editor

The editor must:

[x] list translation per domain
[x] select a translation
[x] save translation
[ ] not allow saving empty translation
[ ] change source/target locales (reload translation list + selected translation)
[x] change domain (reload translation list + keep selected translation?)
[ ] select first translation on page load (on domain change ?)
[x] approve/unapprove a translation

Later:

- select next item 
- keyboard navigation
- filter translation list