Add spires_cpp package with octomap utility for reconstruction filtering

[YifuTao]

spires_cpp

This pull request primarily adds the spires_cpp package which include pybinded cpp script to run Octomap and PCL. The Pybind functions are

1. processPCDFolder: build an octomap from a folder of pcd files with viewpoints. The output is a .bt file
2. removeUnknownPoints: take in a pcd and octomap, and filter points in pcd that is unkown in the octomap. This is used before evaluating the reconstruction to remove outliers
3. convertOctreeToPointCloud: visualise an octomap with a occupied cloud and a free-space cloud

TODO

we can package it so that one pip install is sufficient. A good example is transformer_grammars. Also need to add a dockerfile

Other improvements

• add function to convert e57 cloud to pcd
• add function to modify pcd files' viewpoint with both open3d or pypcd4
• add more se3 functions and checks
• add initial reconstruction benchmark script that does the cloud filtering