Update increaseticks sleep strategy

[kklobe]

This is an experiment to improve the accuracy of the engine that is increaseticks. PIC_RunQueue is at the mercy of the 1ms sleep_for, which can cause an entire millisecond tick to be missed. By lowering the sleep time, PIC_RunQueue can run more often. This allows it to get closer to the precise time specified when an event is added via PIC_AddEvent; many calls throughout the codebase provide sub-millisecond or fractional delays.

Also, it keeps track of the excess microseconds after each sleep and adjusts ticksDone for more accuracy during cycle guessing, since sleep_for isn't precise; for example, a 1ms sleep is actually ~1150-1200us on my M1 Mac, causing it to think it slept for a total of 10 ticks when it was really 11.

None of this should provide a massive difference, but it should give much more accurate responsiveness within ticks. I did notice a difference on the Future Crew Panic demo, on the first 'scrollers suck' portion, with fewer flickers compared to main. At best, it will help smooth out micro-glitches in audio and video here and there, and worst case it should be identical to main.

The one wild card is the new sleepDuration:

constexpr auto sleepDuration = std::chrono::microseconds(100);

On my M1 Mac, it significantly reduces CPU usage compared to 250 or 500 (and even 1000), but that is completely up to the Host OS scheduler. I wanted to start with an aggressive value, and we can back it off if empirical testing warrants.

[johnnovak]

Nice one @kklobe! Definitely a welcome improvement, I'm only hoping the current inaccurate sleep behaviour doesn't mask some timing related emulation deficiencies. But we will see!

[johnnovak]

Looks ok, I guess we can just merge and live with it for a while and see what happens!