Button to wipe current URL; SHA1 is GUID for commit

This changes the internal storage keys and is backward incompatible

close #7
close #9
Use canonical SHA1 of commits instead of one from URL

Close #11
Make #diff-1 hash in URL work

If there's sth like #diff-1 in the URL, GHA was not expanding the mentioned
diff. It was only expanding diffs mentioned by long hashes.
README credits
LICENSE
Added storage.getEntries API; hack-fix for GitHub slow-events
Exporting code review status to the URL hash

So far without option to load it back
Refactor namespaceify
Make JSHint happy
Output hash length
Deserialize API
Refactor export/import buttons
Serialize/deserialize works finally

Close #8.
Confirm deserialize
Expand unreviewed

Close #4.
Nothing to import/export info
jshint, L10N
Configuration Dialog
Refactor some settings
Settings dialog, little refactor