adds preview handling to content_editable module.
allows binding to any global event by prefixing it with mercury:
builds out some more of the UI.
moves some locales over and starts the migration process (will do more when I get bored)
adds more interface configuration.
adjusts region.

- adds a reference to the region instance on data-region.
- adds the ability to track changes/reset that on save.
fixes an issue with serializing selections.. revisit some other time.
adds onbeforeunload for prompting on navigation when changes are present.
builds distro.
backfills some specs.
updates distro.