New module for session-based roaming like in Netscape Communicator 4.x.
r=Pete Zha <pete.zha@sun.com>
sr=darin (backend), jag (UI code)
a=tor
Tracking of bugs, regressions: Bug 228629
git-svn-id: svn://10.0.0.236/trunk@156859 18797224-902f-48f8-a5cc-f745e15eee43
