Fix issue with search by image button labeling for Jul-19 site version.

Update zh_CN and zh_TW translation (bijij#197)

* update zh_CN translation

* update zh_TW translation

Clean up code, bump version number for release.

Bump version number for release

Fix issue with env var in gh-actions deploy

Fix typo in moz publish config

localise donate text

update readme

remove unused var

release 1.6.4:

 - Fixes issues with buttons sometimes not appearing on search by image pages