improved the thread creation.
changed the implementation of switching Text/MIME view.
improved MimeView and file selection dialog.
replaced GtkFileSelection with GtkFileChooserDialog.
changed the indent size of summary.
fixed non-utf8 filename handlings.
replaced intl.h with glib/gi18n.h.
improved font management.
use GTK stock button for dialog button set.
restored the resize grip of the main statusbar.
fixed a bug that didn't correctly get text selection on reply.
Initial import of Sylpheed (GTK2 version).