Ergonomics: size thread pools dynamically

Ergonomics are a step towards less configuration and more dynamic setting of values. Example: a thread pool's min and max sizes can be dynamically changed, based on observations. When we have a min size of 10, but the thread pool is always 75, then we should set the min size to 75 and possibly change the idle time too.

This is just a first step towards ergonomics and needs to be expanded on in 3.x releases