Adding release checksum.

Signing v1.2.0

Added tag v1.2.0 for changeset 02dfe3df786a

Bump minor version, update history, remove old files

Update for Ruby 3, unhoe-ify, improve API docs

Fix the defaultdb build and use the sqlunet50 db for PostgresSQL testing.

Update data-dir calculation to use newer Rubygems API

Fixes #5.

Added tag v1.1.0 for changeset 3e0c43a8c8f0

Added signature for changeset b43660cdab72

Update history files

Update defaultdb build files

Simplified default DB code

Update docs

Add a few more documentation fixes

Convert to modern symbol-hash syntax.

Update documentation

Update the wordnet-defaultdb gem to use the latest SqlUNet distro

Update my gem-signing cert

Update to WordNet 3.1, Sequel 5.0.

- Made tests run under both Sqlite and PG.
- Removed deprecated syntax/conventions from Sequel < 5
- Move to Ruby 2.4 as primary tested version, though 2.3 is
  still supported
- Made fetching Synset by ordinal deterministic

Update the README