Calculate dynamically Object3D center

[jscastro76]

Objects3D can have different positional and pivotal center depending on their objects. 3D loaded models pivotal center is normally defined in the model itself and for Three.js geometries, the positional and pivotal center is x/2, y/2, z/2.

For accurate and standard positioning across all 3DObjects, the center of any object must be calculated and then redefined based on a param, similar to what is done in Mapbox for (Markers)[https://docs.mapbox.com/mapbox-gl-js/api/markers/#marker] where options.anchor could have these values 'center' , 'top' , 'bottom' , 'left' , 'right' , 'top-left' , 'top-right' , 'bottom-left' , and 'bottom-right'

[jscastro76]

v.2.0.4.