* C/usage-mainwindow.sgml: Redid menubar description.
* C/config-prefs.sgml: Added coverage of folder config, requested
that feature be transferred to config section. Switched to
variablelist in "Other" config section.
* C/usage-mail.sgml: Added coverage of right-click on messages,
threaded-view.
* C/usage-mainwindow.sgml: Right-click on folder menu reinstated.
svn path=/trunk/; revision=4650