Port mainstream patches

[JakMobius]

This version of Box2D is affected by flyover#79. b2BroadPhase.UnBufferMove does not remove some proxy moves resulting in assertion failure in b2BroadPhase.UpdatePairs. The suggested fix is to port flyover@48e167c.

[JakMobius]

Also, I suggest considering the rest of the patches as well. It seems like Box2D has received plenty of updates in the last three years.

[Lusito]

I switched mainstream to the original (Box2D from Erin Catto).
The last time I merged changes from it, was june 2024, so that should be up to date (aside from the Switch to Version 3).

This particular code snippet, I must have overlooked when comparing the code with the original. I'll supply a fix for that.

I've skimmed over the changes from flyover and the only ones that seemed like they have not been refactoring/cleanup commits or upstream changes (from Original), which I've done myself already, are these:

flyover@1d2cc3a#diff-eb7280cee2bd76f87794feeb11aba32b708b60cebb310977a8f1f07f69189477

flyover@c9bf588#diff-b7b2e775ba814d459e85a01d20a5c04cfa9f38ff82380d9bd887dbe798f6d22f

And they seem more like features and changes that to not relate to the Original. Not sure if I want to port those changes. Feel free to offer reasons.

[JakMobius]

I don't insist on porting these changes; it was just a general suggestion. Since you had this bug in your codebase, I thought you were using a three-year-old version.
It's interesting how you ported all the fixes except for this specific one. Back in 2021, I contributed to fixing the same bug in the original Box2D. I was surprised to find the same bug here. Isaac didn't use my pull request back then, so I'm glad to have another opportunity to formally become a contributor. Hope you approve!

[Lusito]

The way I compare changes with the c++ version requires high attention. I guess I must have thought, that this was an improvement for JS that flyover added to avoid going over all elements. I didn't realize, that a proxy could exist multiple times in the array.

I've added a review to your PR. When that is cleared, I'll merge. Thanks!