@since tags no longer needed
Complete a todo item
Inherit parent's title attribute when creating a a popdown element
Add title information to message actions
[mms] Don't persist dynamic filter views across page reloads.

Conflicts:
	imp/docs/CHANGES
	imp/package.xml
Error/sanity checking when calling IMP_Contents#getMIMEPart()

Return is allowed to be null (e.g. failure to connect to IMAP backend),
so need to check for that everywhere we use.
getMIMEPart() -> getMimePart()
Remove old, unused preview code