Fixed bugs and crashes as a result of iso-surfaces being highlighted. Tracker item 2747, https://tracker.physiomeproject.org/show_bug.cgi?id=2747
Fixed bugs and crashes as a result of iso-surfaces being highlighted. Tracker item 2747, https://tracker.physiomeproject.org/show_bug.cgi?id=2747

git-svn-id: 4705079bc6b8aadf675e3696f5c015a6aa4916e3@8125 3c1deb5b-d424-0410-962d-aba41a686d42

hsorby/zinc,OpenCMISS/zinc,hsorby/zinc,hsorby/zinc,OpenCMISS/zinc,OpenCMISS/zinc,hsorby/zinc,OpenCMISS/zinc