Fix and clean up editing project settings
Use notFound instead of status_not_found
Clean up error handling
Remove some obsolete JSON APIs
Remove already disabled jobstatus code
Remove the Errors page

The same info is readily available under the most recent jobset eval
page.
Remove obsolete JobStatus source
Remove more dead code
Fix tabs
Ensure proper encoding of error messages
Use the REST API in the web interface for editing projects
Implement DELETE for jobsets and use it in the web interface
Instead hard breaks in multi-line error messages
Use the REST API in the web interface for editing jobsets
Simplify jobset cloning

We can just show the normal "edit jobset" page for the original jobset
and then do a PUT request to create a new jobset.

Also simplified updating the jobset inputs.  We can just delete all of
them and recreate them from the user parameters.  That's safe because
it's done in a transaction.
Use delete instead of delete_all

DBIC's delete_all method fetches all rows separately, which is slow.
Restore link to clearvcscache
Use more flash messages