window: Update about dialog

This work removes the manually curated lis of contributors, both because of its maintenership burden and because contributions come from a very diverse sources, including marketing, QA, translation, design, mouth-to-mouth preaching, etc. By creditting just a few of them we undermine all the others that make such a great and sometimes invisible effort.

This also updates the program name to mention the codename Nautilus, so those looking at the about dialog, most likely developers, know the code name of the project.

And finally, it adds the website so people know where to find more information, issues, and to contribute.