Add support for Safari

[wheelercj]

Stardown is available for Firefox, Chrome, and Edge. It can also be installed on all other Chromium browsers that use Chrome's web store such as Brave, Vivaldi, and Opera.

However, Stardown is currently not available for Safari. I would like to create and release a version of Stardown for Safari, but there are some roadblocks:

1. I don't have a Mac. As far as I can tell, creating Safari extensions requires using a Mac.
2. I'm not in the Apple Developer Program which also appears to be required for publishing Safari extensions. The Apple Developer Program normally costs $99 USD per year in the United States. According to this Stack Overflow discussion, when one's program membership expires, everything they published is removed from the app store.

Since Stardown is free and doesn't display ads nor harvest data, it doesn't make much sense for me to pay to support one browser that is not the most widely used.

I'm not sure what to do yet because there might be legal issues with allowing someone else to release Stardown in Apple's app store. When I have time, I'll look into this more and think about it. There's a chance I could borrow a relative's Mac and, if there is enough interest in Stardown, maybe I could get some donations to cover the fee. I'm quite confident that I would not be able to get the Apple Developer Program fee waived in the foreseeable future.

[wheelercj]

In case anyone is keeping an eye on this, I have made up my mind. I will make a Safari version of Stardown and release it on Apple's app store! There will be a small fee to help cover the cost of keeping Stardown in the app store. I can't give an exact release date yet because Stardown is still early in development (I released the extension to the other browsers earlier than I should have), but I hope it will be ready sometime in June.