Multiple issues with cropbox

[kavnat]

cropbox.py has multiple issues:

1. The C++ code in the comments suggest that make_cropbox works for pointcloud_pointXYZI, but its not true. I am getting attribute error. make_cropbox is working only with pcl.PointCloud

2. When I try to assign the filter output to a pcl pointcloud, python crashes everytime.

outcloud = clipper.filter() pcl.save(outcloud,"frame.pcd")

[Miriup]

Issue 1 duplicates #123.