"Open in Default App" broken on macOS and iOS

[craigeley]

Closing #114 to be more specific with the actual issue.

As mentioned in #107, the "Open in Default App" button does not work on iOS, and I can confirm that it also doesn't work on macOS. Those platforms do not seem to support the geo URL scheme, which means that option / button appears to be broken for users on those platforms.

I think one solution would be to add a check box to make a custom "open in" action the default app. Then iOS users could have that button at least do something.

Thanks!