Even more verbose errors.
Clearer error reporting when no such version exists.
Flatten logic for versioned_install.
Replace changeset terminology with commit.
No longer require fully specifing path with vinstall.

Will attempt to infer correct tap from `brew info`. Update examples to reflect this and the switch over to allow executin as brew external commands.
Refactor to make with statement based git checkouts more literate.
Refactor to break further break up versioned_install.
Fill out vinfo command to get an info JSON dict for installed versions.
Bug fix related to parsing out specific kinds of dependencies from `brew info`.

Not really using this yet but it does appear in new `brew vinfo` command.