Implement preemptive multitasking #3036
Description
See this forum thread for why current implementation of "kill coroutine after N seconds" does not really cut it, and for proposed solution. Basically, I suggest implementing preemptive multitasking between different computers. Ability to implement preemptive multitasking within a single machine is just a bonus.
See evg-zhabotinsky#5 for my internal WIP PR of the actual implementation. Current status is "mostly solves the executor hogging problem, but requires a bit more work to stop breaking persistence". More fair scheduling and userspace API are TODO.