Force signin plugin

[sam (Sam Saffron)]

How does this compare to?

Guest Gate (Sign Up Popup Plugin)

This is a more permanent post for a plugin that @vinothkannans created and I forked recently. Many thanks to @vinothkannans for doing the hard work of wiring up the main logic, @ljpp for stirring the original conversation, and @DiscourseMetrics.com for providing the impetus behind a customized modal. This plugin was abandoned and in Sept 2019 maintenance was taken over by @michaeld. https://github.com/communiteq/discourse-guest-gate As with all plugins, this is how you add it: - git clone ht…