Newbeat

[davepl]

Description

Adds actually useful/accurate beat detection. Updates the Stars effect to use it. Adds a blue "near miss" and red "beat detect" in the center of the VU meter. Not permanent, necessarily.

• I read the contribution guidelines in CONTRIBUTING.md.
• I understand the BlinkenPerBit metric, and maximized it in this PR.
• I selected main as the target branch.
• All code herein is subjected to the license terms in COPYING.txt.

[rbergen]

This PR includes the changes proposed in #857 - which is still in progress of being reviewed - and as such builds on that one.

I'll therefore hold on reviewing this PR until #857 is either merged or closed, so we can focus on the delta between the two.

[rbergen]

LGTM, explicitly also applying to the changes originally introduced in #857.