Transition to new translation system.
Refactor Option.isDefined checks.

Next up is Option.isEmpty, but that will likely require non-local
changes.
Further Option safety improvements.
Removing more unchecked gets
Ensure activity records are deleted with users.

TODO: Change 'actor' to 'userId'. Pretty sure that naming inconsistency
is what caused the problem in the first place. Unfortunately, this
requires a database update.
Adding robustness against ResourceLibrary errors

The resource library wrappers now all return options, to account for the
possibility that requests may fail.
Make content tiles open in a new tab/window

TODO: Ractivify the content list renderer, weed out JQuery & Mustache.
Update translation handling

Also fix some whitespace.
Added related-docs download links