Ubiquerg

Changed
- in `size` function, if a file is not found a warning is issued, instead of a message

Added
- `VersionInHelpParser` methods characterizing the instance:
- `arg_defaults`
- `dests_by_subparser`
- `subcommands`
- `top_level_args`
- `subparsers`

Added
- `uniqify` function
- support for collection of paths in `size` function

Fixed
- path expansion issues; [Issue 24](https://github.com/pepkit/ubiquerg/issues/24)

Changed

Added
- add `asciify_dict` function

Added
- add `--version` argument in `VersionInHelpParser`
- add `untar` function
- add `mkabs` function

Added
- `parse_registry_path` function.

Fixed
- `is_writable` function; [Issue 16](https://github.com/pepkit/ubiquerg/issues/16)