v0.15

Still very much a work in progress! The core data structures and algorithms seem to perform well. But the CLI isn't clean and intuitive yet, the docs aren't written, and there are a few funny edge cases I worry about regarding unprintable-but-technically-valid filenames. Suitable for adventurous users willing to double check things before deleting them. This release is Linux only because I'm working on the MacOS static build next.