Slot Viewer: (1) Slot Callbacks, (2) Slot Deletion Processing
Bug Number: n/a
Release notes (y/n): no
For Release Nums: 7.2

Slot callbacks had not been maintained at the right level.  Some Slot callback 
registrations were being made, but not in all places where the list of slots 
within the Slot Viewer is modified.  This has been reformulated such that each 
time a revised set of slots is provided to the SlotDataTableModel class.  

   See method SlotDataTableModel::setGeneratorSlotList() and its call to the 
   new mehtod: SlotQtDlg::generatorSlotListSet().  (Slot callback 
   registrations are maintained within SlotQtDlg).

With slot callback registrations working properly, a few problems with Slot 
Deletion became apparent.  There was an especially difficult problem with 
the QMap used to preserve column widths (of particular SlotColRefs).  
Ultimately, I needed to know if calls to SlotDataTableModel::
setGeneratorSlotList() -- mentioned above -- were part of the process of 
handling a SLOT DELETION (but not removal or addition of slots from the 
Slot Viewer, i.e. which were not themselves actually being deleted).  

The following methods now have additional parameters to support 
this mechanism:

   void SlotDataTableModel::setGeneratorSlotList (
      const QList<SlotColRef>&, bool forSlotDeletion);

   void SlotDataTableModel::recordSlotCol_colWidthMap (
      QMap<SlotColRef, int>& colWidthMap,
      const QList<SlotColRef>* limitToSlots) const;

And the following methods were added:

   void SlotQtDlg::generatorSlotListSet();

   void SlotQtDlg::slotViewer_removeSlotColRef (
      SlotColRef scRef, bool slotWasDeleted);

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