Add structs for depth and world coordinates and for color
Use struct DepthImageCoordinates for DepthImage
Use struct DepthImageCoordinates for DepthImage
Split Point into an interface and a implementation for OpenNI2 points
Use new instead of make_shared to increase performance
Add a struct for depth image size
Add a clone function to Point
Add a clone function to Point
Add a struct for depth image size
Handle point memory ourself as std::shared_ptr has a too big overhead

Now we are faster but still not fast enough