Allow additional URL schemes

The composer does not allow the use of uncommon URL schemes in hyperlinks, and does not automatically linkify URLs using uncommon URL schemes. Also, links in incoming messages that use uncommon URL schemes are silently blocked. They still appear to be links, but do not respond to left- or right-clicks.

It would be helpful if it were less discerning, or if we were allowed to whitelist additional schemes.

For example, our internal ERP software handles the "fmp" scheme, as in:

fmp://server.name/module.name?command-name

Being able to use clickable links to our ERP system would be very useful!