Add a pair of improved visibility badges.

Add a "geometric" and a "hierarchical" visibility badge to SMTK's ParaView extensions.

Figure 1. An example of the resource browser with the two new badges.

The geometric visibility badge appears next to phrases whose objects have renderable geometry and is either a solid black box (visible) or grey box (blanked/hidden).

The hierarchical visibility badge appears next to phrases with children and has a lower (child) box that is either:

• solid black, indicating all children are visible;
• light grey, indicating all children are blanked/hidden; or
• medium grey with a minus sign, indicating children are in a mixture of states.

The resource browser can be configured to use

• these two new badges together (now the default);
• the new geometric visibility badge without the new hierarchical badge; or
• the old visibility badge.