I should be able to change the Type of a Property

(User Story, Investigate , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Editor, Properties
Summary: This feature used to exist, then fell out when we rewrote the Client.
This needs a bit of design, but should clearly be possible. It should only be possible where it makes sense, though. Initially, at the least, we should be able to switch between Text and Large Text freely.