Pclpy

Features
- PCL doxygen documentation is added as docstrings in classes and methods
- Simpler, more pythonic api (see pclpy.api)
Api changes
- simpler function calls
pclpy.read instead of pclpy.io.las.read (tries to guess file format from extension, even if there is only las for now)
pclpy.read_las instead of pclpy.io.las.read
pclpy.write_las instead of pclpy.io.las.write
pclpy.Viewer instead of pclpy.view.vtk.Viewer
Viewer().viewer becomes Viewer().pcl_visualizer
- shorter constructors
pcl.PointCloud.PointXYZ.from_array(a)
is now the same as
pcl.PointCloud.PointXYZ(a)

bugs
- other bug fixes

- [feature] The pypi wheel is built using the vtk binaries included with conda. So It's possible to embed a PCLVisualizer inside a window (PyQt/wxWidgets/etc.) A simple example is provided in `pclpy/examples/pcl_with_pyqt5.py`
- [feature] Array properties are now accessible as a numpy views
- [api change] For colored point clouds, replace ambiguous "rgb_reversed" property with rgb and argb
- [bug] Some class names included illegal python symbols (`octree::OctreePointCloudVoxelCentroidContainer<pcl::PointXYZ>` becomes `OctreePointCloudVoxelCentroidContainer_PointXYZ`)