Add gitignore entry for Qt Creator user files
Add gitignore entry for Qt Creator user files

stiXits/demo_ter,stephde/CG2Uebung,stiXits/demo_lod,stiXits/demo_ter,stephde/CG2Uebung,stephde/CG2Uebung,stiXits/demo_ray,hpicgs/cg2sandbox,stiXits/demo_ray,stiXits/demo_ray,lanice/cg2sandbox,lanice/cg2sandbox,stiXits/demo_lod,lanice/cg2sandbox,hpicgs/cg2sandbox,stiXits/demo_ter,stiXits/demo_lod