[mms] Fix edit links for virtual folders in dynamic view.

[mms] Fix links to virtual folders on search preferences page.
[mms] Fix APPENDs on remote IMAP servers that do not support CATENATE.
Merge branch 'master' into imp_6_1

Conflicts:
	imp/docs/CHANGES
	imp/lib/Prefs/Special/Searches.php
	imp/package.xml