add .gitignore
add .gitignore

robotology-playground/Robust-View-Graph-SLAM,robotology-playground/Robust-View-Graph-SLAM,robotology-playground/Robust-View-Graph-SLAM,robotology-playground/Robust-View-Graph-SLAM,robotology-playground/Robust-View-Graph-SLAM,robotology-playground/Robust-View-Graph-SLAM