The trait of this implementation is that it doesn't use priority queue and
time scheduling, and instead does its all operations using polling, starting
with such basic one as sleep. On the other hand, this tries to implement
all (well, much) of upstream asyncio API and warts.
asyncio_slow: Rename from asyncio_micro.
It may turn out that this won't be "micro" at all. The main trait of this
implementation is that it stay 100% API compatible with upstream (in
those APIs which are implemented of course). It will also keep inefficient
implementation of event loop scheduling, to discourage its use. Here we go.