Add option to hide and reset form on submit

[buzztone]

“on_sent_ok” and its sibling setting “on_submit” are deprecated and about to be removed in the next version of Contact Form 7- v5.0 - see https://contactform7.com/2017/06/07/on-sent-ok-is-deprecated/

contact-form-7-extras could be extended to cover following items done previously using on_sent_ok:

• Hide CF7 form after sent - http://www.asapchange.com/hide-contact-form-7-after-successful-send/
• Reset form - https://www.techiecorner.com/2732/contact-form-7-clear-all-field-except-specific-after-submission/

CF7 author recommends using https://contactform7.com/dom-events/ to replace on_sent_ok.

As CF7 has over 6 million active installs, I expect there are several 100,000 sites using on_sent_ok. That is potentially a lot of people how are going to have partly broken CF7 forms when Contact Form 7 v5.0 is released around the end of Jan 2018.

contact-form-7-extras already provides an alternative to using on_sent_ok for following common uses:

• Redirect to another page - http://contactform7.com/redirecting-to-another-url-after-submissions/
• Tracking form submissions - https://contactform7.com/tracking-form-submissions-with-google-analytics/

It might make sense to extend support to these other on_sent_ok uses.

[kasparsd]

Thanks @buzztone! This was already reported in #10 and fixed in #13.

[kasparsd]

@buzztone Oh, sorry -- this was about adding two new "hooks":

• Hide CF7 form after sent
• Reset form

I'll re-open it and rename it to clarify the feature request.