Variable playback speed

Since the original release of hCore it’s been possible to play back simulation runs at a fixed speed (sped-up or slowed-down, depending on your preference).

We’ve now introduced the ability to specify steps-per-second play speed ahead of time, so that you can compute and playback at a fixed pace without multiple button-clicks.

This makes it possible to more quickly reset and play simulations at a sensible speed whilst prototyping, and share simulations with others in the manner they’re meant to be seen.