I thought the change over was 14/11/17 then I read 28/11/17 which also included legacy add-ons would not be fully gone until firefox 58 or 59 - what the truth is , is anyones guess
No script from what i've read should work on firefox 57
Plenty of other alternatives but alas you'll find a lot of add-ons will simply be gone
because they werent popular enough or developers have no interest in continuing
The upgrade to 57 and web extensions replacing add-ons is meant to stop improvements to the browser disabling any add-ons / web extensions which has caused plenty of users to abandon them.
RapidRelease/Calendar
https://wiki.mozilla.org/RapidRelease/Calendar
Firefox 57 release overview
https://www.ghacks.net/2017/11/13/fi...ease-overview/
This browser is probably the closest to firefox but without all the baggage
Has many of the same add-ons like no script
www.palemoon.org
has a list of compatible / forked or Known Incompatible Add-ons.
https://addons.palemoon.org/
Image host grabber direct link
https://imagehostgrabber.com/download.html
other developers have gone to
https://www.seamonkey-project.org/
This might be useful
FEBE
by Chuck_Baker
FEBE (Firefox Environment Backup Extension) allows you to quickly and easily backup your Firefox extensions. In fact, it goes beyond just backing up -- It will actually rebuild your extensions individually into installable .xpi files.
https://addons.mozilla.org/en-US/firefox/addon/febe/