fixed compilation error with Fink + OS X (Bug #42).
added new plug-in signals to notify start and end of receiving.
changed the spec of compose-send signal because the previous one prohibited sending if the signal is not used.
added a new plug-in API: 'messagev-ew-show'.
added a new plug-in API: 'compose-send'.
modified textview-menu-popup plug-in signal.
added 'textview-menu-popup' signal for plug-ins.
merged plug-in update check and automatic update patch.
attachment_tool.c: skip multipart messages without attachments.
attachment_tool.c: don't keep backup.
added Attachment Tool Plug-in.
added plug-in APIs to get selected messages on summary.
added new plug-in APIs for manipulating the summary view popup menu.
fixed syl_plugin_folderview_add_sub_widget() and updated test plug-in.
plugin/test/test.c: added tests for compose.
added new plug-in APIs for compose window.
fixed build issue.
do not install test plugin automatically.
merged plugin-test branch into trunk.