Issue #3201620: D7: Integrate invisible captcha

added 7 commits

• 601c1c19...ebef01fe - 5 commits from branch project:7.x-2.x
• 0ddcba4d - Issue #3201620 by jedihe, mr.york, chgasparoto, sokru, veret, TimRutherford,...
• 2f9a6da0 - Multiple buttons, proper event handling.

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