Also, fix submission without a lock and locks are disabled

Fixes #2372
Fixes #2361

- Adds mass assign, transfer to ticket queues
- Retire inline forms for ticket assignment and transfer

Fixes #2364

Fixes #2371

And two flags, one which signals that stored HTML is correctly balanced and
does not need to be balanced when rendered in the ticket view. The second is
used to signal messages received from collaborators.

Additionally, this patch fixes showing external inline images (via the [Show
Images] button) when clicked.