work on normal computing

Fresh pull request from main repository.
Applied the work of colincsl
Corrected it to no more use at function
workaround a Cython bug? can't use regular
T *getptrN(pcl::PointCloud<T> *pc, size_t i)
, even if in htoery with templates it should be okay. Add to duplicate code.

It compiles, I don't know if it works due to local trouble with pcl.