1) Memory leak fixed:
 when the plotting destination set to replace, cloned objects with the canvas
 about to be closed are now being deleted first.
2) Group restore fixed:
 when restoring a saved session, and objects from file subdirectories were
 added to a group, they were not being included in that group.  Now the
 data file is searched recursively for subdirectories.
3) Group draw fixed:
 TH2 and TH3 objects in a group were not being drawn.