cppcheck exception
add nite::UserTracker successfully

two topic added:

/camera/num_users: number of users being tracked
/camera/user_map: image showing segmented users each one painted in a different color
added modified files
Update README.md

add instructions to visualize the user map
add example image of user map
Merge branch 'add_user_tracker' of https://github.com/pal-robotics/openni2_camera into add_user_tracker
Update README.md

center user map example image
draw skeletons in user map
Merge branch 'add_user_tracker' of https://github.com/pal-robotics/openni2_camera into add_user_tracker
publish persons position wrt RGB-D camera
Document /camera/users topic
Merge pull request #1 from pal-robotics/add_user_tracker

Add user tracker