Simplify f-root implementation.
Simplify f-path-separator implementation.
Return nil if asking for parent of root.
Simplify f-parent-of? and f-child-of?
Fix typo in README.
If root, f-parent return nil.
Simplify f-root even more.
Fix typo in README.
Update Changelog.
Merge branch 'v0.12-wip'
Release v0.12.0.