NNC: Improved visual effects

Removed use of depth buffer manipulation as this caused invalid result
color mapping for NNC when combined with other fault geometry.
Use polygon offset on NNC geometry to make sure NNC always wins
Show combined transmissibility first in list
Updated defaults and modified GUI labels
Toolbar: Added button control for toolbar labels
Show fault name in Result Info when picking NNC
Result Info: Show fault name only when picking on fault
Improved tool button image
Use setValueFromUi to update connected editors when pushing toolbuttons
Replace space with underline in snapshot generated filenames