Release new version 2.12.1

-2.12: Fixed an issue with the back button in Safari & YouTube. (#350)
-      Fixed an issue in the Chrome Beta version if the report an issue link in the popup menu. (#347)
+2.12.1:  Fixed an issue with the back button in Safari & YouTube. (#350)
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+2.12: Fixed an issue in the Chrome Beta version in the 'report an issue' link in the popup menu. (#347)
-      Added a work around to a Chrome bug for incorrectly reporting the type of a URL request. ((#339)