Fs.archive

Removed
- `fs.proxy` dependency.

Fixed
- Metadata not being copied with files in `WrapWritable`.
- `TarFS.extractfile` returning an incomplete file-like object.

Changed
- Properly implement `WrapWritable.scandir` instead of relying on `listdir` and `getinfo`.
- Bump optional `pycdlib` minimum version to `1.3`.

Added
- `iso` extra for reading and writing ISO disk images with the `fs.archive.isofs` module.

Fixed
- `fs.opener.errors` changing name in `fs` version `2.0.7`.
- `Info` properties requiring some namespaces since `fs` version `2.0.8`.

Changed
- Make `open_archive` yield read-only filesystems if the source is read-only.

Initial release.