Split out openni calls in open() into openstreams() to allow NiTE class to override
check that openstreams() returns true
Changed ofxONI2.h to use virtual keyword and protected members for inheritance in ofxNiTEUserTracker
Added ofxNiTEUserTracker. No usertracker specific functions yet.
Added user tracker example program.
example-simple/README.md formatting
Merge branch 'master' of https://github.com/luteberget/ofxONI2