Mojave support and the Safari Extension Gallery

[benlachman]

It seems like this repository has been unmaintained since sometime in 2016. With the imminent release of macOS Mojave, which makes it significantly harder to run extensions that are not signed, I wanted to toss out an option I ran across today: Smilematic. It's roughly the same thing and is already in the Safari Extension Gallery.

[bosmacs]

Getting KeepOnSmiling signed and on the extension gallery has been on my TODO list for a long time; Mojave/Safari 12.0 has forced the issue. I will look into this as soon as I can spare the time.