The editor render callback property allows a content type to define the way it should be rendered in the display editor itself. This is useful if there are circumstances in which you really _do_ need to have the content preview displayed (which, as of beta4, is disabled).

Very big documentation update: added first plugin sample/api doc, for content types. Docs.inc was updated with new glossary terms and to use the new doxygen aliasing system.

Initial commit of custom doxygen file; all it really does is cap the main navigational width at 900px.

#260221 by sun, Pancho. Primarily codestyle cleanup; also fixed some missing leading slashes that were causing the edit icons not to appear in the new helptext for the display editor.