Before, extensions were missing the definition of mandatory methods.
At the moment, it's not a problem because the coding guidelines are not
enforced by the code. But in the future, it will break.
Now, extensions have all mandatory method definitions.
* Update to 1.2
* Fix display when article top bar has been changed by the user
Fix https://github.com/FreshRSS/Extensions/issues/58
Co-authored-by: lapineige <lapineige@users.noreply.github.com>