Devlog 4: The Night Sky Background

Finished the work on the background. The star sizes are randomly assigned based on a power law distribution to make them look believable. The colors and the opacity is calculated from the size, similar enough to real stars. The graphic resizes to the window size, and up-scales on hi-dpi displays.
Also added backgrounds to the text, to make it more readable. And I fixed the wrong github link (it was redirecting to some weird site)