implemented tray icon in Win32.
don't enable trayicon action if modal window exists. Present window on click if main window is obscured.
disable Send button if no account exist.
perform show/hide on trayicon click. Implemented popup menu on trayicon.
update progress bar when executing long IMAP4 operations.
separated some enums to reduce dependency.
separated trayicon into another module, and notify new messages with trayicon on receive.
initial implementation of the tray icon.
added a feature for junk mail control.
restored the resize grip of the main statusbar.
Initial import of Sylpheed (GTK2 version).