Planet Renderer notification on first launch

[Ytse Frobozz]

Hello! Very excited about this effort. I think most people who care know about this by now, but I think it would be helpful to give some kind of indication that the "Planet Renderer" can take a long time on first launch. The first time I ran the program, I thought it was crashing when I really just needed a little text to let me know that I need to be patient. Thanks for all of your hard work!