Propose adding live addition of redirects

[mikeselander]

As is, the plugin allows "live" deletions of redirects without a page reload, but not additions. The UI of the plugin would be considerably improved by using admin AJAX to create the redirects instead of parsing upon page reload and would allow users to add redirects much more quickly. I've had to add upwards of 50 redirects for a new site using this plugin before and running a submission for every single one gets rather tedious.

You could also tie in validation more quickly and at a granular level with the requests - for instance immediately identify when the data put into the Destination field doesn't match a URL.

I'm willing write a PR for this if it's a feature you're willing to consider.