*8929* Permit tags in TinyMCE fields

We didn't support HTML in email templates before.

I still have to do this, but I'm thinking...
- Add upgrade statements to convert nl2br in email templates already installed in the database
- Run the same on the email template files and commit
This will mean all email templates are in HTML and existing modifications to templates will be preserved.

The body is the HTML version; the altbody runs a simple html to text conversion to provide a plaintext-based email body for readers that don't support HTML.