QTUI symbol list in dock window is now sorted on first population.  Symbol creation events now add new symbol into QTUI symbol list, correctly placed according to sortedness.  Framework in place for QTUI symbol list to respond to symbol deletion, pending disassembler sending said events.  Genericised sorted symbol list maintenance functions from uncertain reference handling, for use in symbol lists and other assorted lists.
When tracking data type changes in order to broadcast uncertain reference changes, fix an edge case where the data type does not change.  Also add a perhaps temporary marker to automatically generated label names to indicate that they are relocated addresses (helps know when looking for references in the UI, for an existing label, but none are found).