added plug-in API for notification window.
added safe mode (don't load plug-ins).
removed 'dereferencing type-punned pointer will break strict-aliasing rules' compiler warnings.
added new plug-in signals for preferences dialogs (#30)
added new plug-in signals to notify start and end of receiving.
added a new plug-in API: 'messagev-ew-show'.
added a new plug-in API: 'compose-send'.
added marshaller for plug-in library. made 3.1.0rc.
modified textview-menu-popup plug-in signal.
added 'textview-menu-popup' signal for plug-ins.
merged plug-in update check and automatic update patch.
added new plug-in functions for sending messages.
added plug-in APIs.
added syl_plugin_summary_show_queued_msgs() and cleanup the code.
added plug-in APIs to get selected messages on summary.
added new plug-in APIs for manipulating the summary view popup menu.
added write lock mode on summary view.
fixed syl_plugin_folderview_add_sub_widget() and updated test plug-in.
added plug-in APIs for folder view.
added some functions for FolderView.
added functions to modify URLs for update check.
added new plug-in APIs for compose window.
added plugin APIs.
added <IMAPFolder> and <NewsFolder> to parent factory.
properly check plug-in version.
added new plug-in APIs.
syl_plugin_load_all(): don't output warning when failed to open directory.
added plugin API.
merged plugin-test branch into trunk.