Fixed bug in pqCoreUtilities::connect.

Incorrect use of HasObserver(). The argument is eventid, not observer
tag. That was resulting in observers never being removed when the
QObject dies before the VTK object. Fixed that.

Change-Id: I671f4fb72b6f26e312f358415a3c668540520f8b
Add ability to create separate pqPropertiesPanels.

pqPropertiesPanel currently shows all properties. Added mechanism for
application to pick and choose which types of properties to show in the
particular instance of pqPropertiesPanel.

Change-Id: Ida28cb1a09b5d1de530a2ebce5daa770235248f0
Add ability to pick how Properties panel is shown.

Added a new setting to control if source, display, and view properties
are to be shown in the same Properties panel or in separate panels.

Change-Id: I9951dcb9b180d742defbf517a26be0ed676acc27
Merge topic 'lookup_table_cleanup' into next

c43a66a2 Add ability to pick how Properties panel is shown.
a18bb45a Add ability to create separate pqPropertiesPanels.
cf422337 Fixed bug in pqCoreUtilities::connect.