It already exists they hid it probably to keep sponsored ones happy, to re-enable:in about:config add the entrybrowser.urlbar.update2.engineAliasRefresh and set it to true; now you'll have back the "add" button in Settings - Search, next to the "remo...
It already existed before and was visible by default, they disabled probably to favor Google, Bing, and other sponsored search engines; you can make it visible in about:config (add the following entry) browser.urlbar.update2.engineAliasRefresh and se...
