[reconstruction] small structural re-organization

* move LiveSfmManager.stepCreated to Reconstruction.sfmAugmented
* add utility methods in Reconstruction to get all images/views used in the graph
* ui: perform local auto-layout on sfm augmentation on created nodes

meshroom/common/qt.py

@@ -223,6 +223,7 @@ class QObjectListModel(QtCore.QAbstractListModel):
         """
         return obj in self._objects
 
+    @QtCore.Slot(QtCore.QObject, result=int)
     def indexOf(self, matchObj, fromIndex=0, positive=True):
         """ Returns the index position of the first occurrence of object in
         the model, searching forward from index position from.