[pitivi] Add back missing Timeline.purgeObject

[Jean-François Fortin Tam <jfft src gnome org>]

commit 1c41f1e24b649fc8f2489db43ab0b24f4ec34ffa
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Wed May 22 01:06:59 2013 +0200

    Add back missing Timeline.purgeObject

 pitivi/timeline/timeline.py |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/pitivi/timeline/timeline.py b/pitivi/timeline/timeline.py
index 38b99ce..3855783 100644
--- a/pitivi/timeline/timeline.py
+++ b/pitivi/timeline/timeline.py
@@ -602,6 +602,14 @@ class Timeline(Gtk.VBox, Zoomable):
         else:
             self.scrollToPosition(self.bTimeline.props.duration)
 
+    def purgeObject(self, asset_id):
+        """Remove all instances of an asset from the timeline."""
+        layers = self.bTimeline.get_layers()
+        for layer in layers:
+            for tlobj in layer.get_clips():
+                if asset_id == tlobj.get_id():
+                    layer.remove_clip(tlobj)
+
     def setProjectManager(self, projectmanager):
         if self._projectmanager is not None:
             self._projectmanager.disconnect_by_func(self._projectChangedCb)