doesn't load the next unread message. thanks to ssu for the initial patch,
and neil for the suggestions. r/sr=bienvenu
fix for #49305. in "view all headers" mode, we only see the last header
for headers where multiple headers are legal. thanks to richard.li@sun.com
for the initial patch. r/sr=bienvenu
fix for #179803. when we added mail views, we added "Sender is[n't] in addressbook"
support to filter / search / views, but it left us with two "Sender" menuitems.
this code unifies them into one. on disk (for filters and views) both the old
way ("from in ab") and the new way ("from") work, so there isn't a migration issue.
r/sr=bienvenu