print_exc() refactoring: adds format_exc()
print_exc() refactoring: adds format_exc()

Nikea/VisTrails,celiafish/VisTrails,minesense/VisTrails,Nikea/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,Nikea/VisTrails,VisTrails/VisTrails,hjanime/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,minesense/VisTrails,VisTrails/VisTrails,Nikea/VisTrails,minesense/VisTrails,celiafish/VisTrails,celiafish/VisTrails,minesense/VisTrails,hjanime/VisTrails,minesense/VisTrails,hjanime/VisTrails