pull: Split SILOFL into SILOFL-1.0 and SILOFL-1.1

pull: Split SILOFL into SILOFL-1.0 and SILOFL-1.1

The title and linked text are for 1.1, but the description includes
[1]:

  The Open Font License (including its original release, version 1.0)
  is a free copyleft license for fonts...

as reported by Donald Robertson [2].

It would be nice if the FSF had separate identifiers or at least
linked to their version of the 1.0 text; for now I'm just minting my
own versioned identifiers in SPLITS and allowing the SILOFL-1.0 JSON
to include the link to the 1.1 text in its 'uris' property.

[1]: https://www.gnu.org/licenses/license-list.en.html#SILOFL
[2]: https://github.com/wking/fsf-api/issues/7#issuecomment-391093115