New unread count code

Removed "leaveMUC" line as it's happening when the chat is closed
anyway. Rewritten unread count code, it even sorta works and feels more
reliable. Improved autoscroll code in conversations page, opening
keyboard is now smooth. Changed build to 0003. Removed getMUCSubject and
leaveMUC functions from XmppConnectivity and getMUCSubject from
MyXmppClient as they're not needed anymore. Hackfixed a stupid bug which
cause "(unknown)" to appear on chat list if message is received before
roster. I need to optimize it though.