Great ursina tutorial

[albfan]

Hi, I found this project and looks simple but complex enough to demonstrate how to use ursina.

I did a series of patches adding some features:

• Allow to read other devices (upstream PR open in ursina Using other input devices pokepetter/ursina#517)
• Navigate easily from menus (upstream PR open in ursina Is it possible to mark some input as consumed to stop input propagation pokepetter/ursina#518)

I tried to split into atomic changes but there's some back and forth.

Will open the PR and if any looks interesting we can work to merge any part.

I open this meta-issue to see if Rally development is stopped (to continue on my fork) or it is open for contributions. If so, I can open an issue for each characteristic