ZoomHeight has been put back into being an extension. This was because configdialog assumes autoexpand was an extension, and the idleconf tests all need at least one extension to exist to be useful. Zoomheight is pointless in almost any modern desktop environment, but it's very useful as an example extension and as a model extension for tests.

I'm going to fix autocomplete and paragraph options. I had their options in the general tab in an earlier build, but it looks like I accidentally reverted it. The rest of the options are in the highlights tab. The bell was in the extension before I got to it. Fixing that and whatever bugs are in codecontext seems outside the scope of this patch.