Check for presence of ArcGIS 10.1 during install

Check for presence of ArcGIS 10.1 or later during installation to avoid
error 1001 later if not present.
Display map number in switch GIS layer window

Display the map number (order) and the map name (for ArcGIS systems) in
switch GIS layer window and display the layer name, map number (and map
name for ArcGIS) in the main window toolbar.