This preproduction release adds the following:
- The Centroid-based Silhouette (cSIL) CVI
- Explicit imports that allow the user to access the CVI modules from the top package level (i.e., `cvi.cSIL`)
What's Changed
* Make imports explicit, add modules to top level by AP6YC in https://github.com/AP6YC/cvi/pull/17
* Feature/csil by AP6YC in https://github.com/AP6YC/cvi/pull/20