Make improvements to vtkSMMapProperty and subclasses

This makes improvements and fixes some issues with vtkSMMapProperty
and its subclass (vtkSMDoubleMapProperty).

See ParaView bug #14205.

Change-Id: Ibd3b1d21f53224516477b46b1bfdf6e14f8a4fa3
Merge topic '14205-map-property-improvements' into next

ef5fd0e Make improvements to vtkSMMapProperty and subclasses
Fixed VRPlugin crashes when loading VR states with interactor styles

Patch submitted by Johannes Zarl <johannes.zarl@jku.at>

Change-Id: If26df65fbd88581399ba663965e0d340f4163ca9
Merge topic 'fix_crash_vrplugin' into next

04956ce Fixed VRPlugin crashes when loading VR states with interactor styles
pqContourWidget is now smarter on deciding what representation to use.

Change-Id: I9843b9cec2ce5704fbbf5b63b7be26fd8360c98c
Make the marker structure consistent across processors

Change-Id: Ibf4c3fbe4873bff7d64cfbc83bfe5ef13af515b0
Merge topic '14208_cth_reader_crash_on_open' into 14209_cth_markers_error_message

Conflicts:
	ParaViewCore/VTKExtensions/Default/vtkSpyPlotReader.cxx

Change-Id: I5ff3c56bc509d9368413a91b882fdf7c374503cb
Merge topic '14209_cth_markers_error_message' into next

a7573fb Merge topic '14208_cth_reader_crash_on_open' into 14209_cth_markers_error_message
022a5ff Make the marker structure consistent across processors
234c0a1 pqContourWidget is now smarter on deciding what representation to use.
No return value is needed in PrepareBlocks.

Change-Id: I5d97e6f1cb4042d0d9834f3778b2259725a8c30a
Merge topic '14209_cth_markers_error_message' into next

e46b211 No return value is needed in PrepareBlocks.