Ward/dialog

This small change to the rarely used Txtzyme plugin is necessitated by changes made in the core client refactoring of several months ago. Our dialog code no longer leaves window.dialog pointing to the dialog dom object. However, the wiki.dialog function opens the dialog and answers the dom object created in this process. We have only to save it if we want to update the dom asynchronously.

I noticed the need for this update when asked to show Txtzyme at the OSCON 2014 Open H/W Showcase.