Windows build: restructuration of CMakeSettings.json and build with Python 3.9
complements on transformations methods (constructors, converters, data access, rotation operators...)
conversion of a tranformation from double precision to simple precision
delete entity method (warning: use with caution, no protection against a C++ object destruction while there are still Python objects handling the deleted object!)
complements on Polyline methods
addChild method for entities
a minimal bounding box function (find a rotation that minimise the bounding box Ox,Oy,Oz) written with CloudComPy (see test026.py and tes027.py)
better scripts to set the environment when running CloudComPy (enCloudCompPy.bat on Windows, condaCloud.sh on Linux)
activate or deactivate c++ debug trace with environment variable CCTRACE=ON
add IDE spyder and jupyter on conda environments (exemple of jupyter notebook in doc/samples)