don't use 'destroy' signal to destroy objects.
added Hebrew encoding.
reimplemented summary view with GtkTreeView.
support GBK (and X-GBK) encoding.
added a menu to temporally change the outgoing encoding to the composition window.
changed the implementation of switching Text/MIME view.
fixed messageview's select all and selection reply.
replaced GtkFileSelection with GtkFileChooserDialog.
replaced intl.h with glib/gi18n.h.
use GTK stock button for button set.
fixed crash when opening 0-numbered message.
removed support for systems which don't support iconv.
Initial import of Sylpheed (GTK2 version).