Remove SWFUpload

[azaozz]

Development on ​SWFUpload stopped more than seven years ago. With WordPress' policy to keep plugins working, we had to ​fork it to be able to do security updates.

Currently it seems only a handful of old plugins are still using SWFUpload. It's time to say Goodbye :)

We would need to "refactor" the integration JS and replace SWFUpload with a standard file field so we don't break the sites that still use the old/outdated plugins.

#40627 was marked as a duplicate.

@azaozz it took 176m35.812s to obtain this for you 🙂

There are ~128 themes and plugins that reference swfobect on WordPress.org: ​https://gist.github.com/westonruter/5000413c23774155aec1840b59989c89

Replying to westonruter:

Great! Thank you!

Looking through that list, most plugins and themes haven't been updated in the last couple of years. However there are few with lots of users:
nextgen-gallery
wysija-newsletters
codestyling-localization
wp-all-import
profile-builder
wp-filebase
flash-album-gallery

So we will have to have some back-compat. Not full functionality, but enough to ensure there aren't any JS errors and there is an upload form field instead of the embedded Flash.