ENH: Enable selection of translucent geometry

vtkHardwareSelector was skipping all translucent geometry and
selecting only opaque geometry. This change enables selection
of translucent as well as opaque geometry.
Totally transparent(opacity = 0.0) is skipped.

Change-Id: I0ced788803a525a59184ca08e005f821cd6cc096
Merge topic '14412-select-translucent-actors' into next

75f778b2 ENH: Enable selection of translucent geometry