pgzhelper library with Actor extensions and screen mode changes

I'm currently teaching a Python game development course to a group of 10 - 11yo. Materials for the course can be found here: https://trinket.io/aposteriori/courses/game-development-with-pygame-zero and it's free for anyone to use.

Currently, there's only one catch-the-falling-object game, but I'll be adding more games with greater complexity over the next few weeks / months. The next one will probably be an infinite runner, but I haven't thought about what comes after that; any suggestions would be appreciated.

As most of my students are coming in with Scratch experience, and Pygame Zero lacks many of the capabilities of Scratch, I've also created a helper library (https://www.aposteriori.com.sg/pygame-zero-helper/) that fills in some of the missing function. The helper library should eventually be retired when these capabilities appears in Pygame Zero itself, but for now it's helping to bridge the Scratch / Pygame Zero gap and I'll likely be adding more capabilities over the next few months.

Not really an issue, just putting this out to share with everyone.

The issue links to the teaching course and the external pygame-zero-helper library, but names no repository files, tests, or specific change. First clarify whether any helper capability should be added to pgzero; a concrete request and acceptance criteria are needed before implementation can begin.

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