recover groups.dox from 2e5f19c76b5c25f5f146952cf3f4ffc539952107 for #24
recover groups.dox from 2e5f19c76b5c25f5f146952cf3f4ffc539952107 for #24

roboticslab-uc3m/xgnitive,roboticslab-uc3m/xgnitive,roboticslab-uc3m/xgnitive