improve execution-pipeline-caching about sim-ecs

[minecrawler]

Note: There already is a method to prepare the pipeline (world.prepareRun()). It will, however, change some internal fields, so it is not useful to prepare another state than the one running.

It should be possible to use this method to prepare a state and pass the result of the method to world.run() and world.dispatch(). This also needs more attention in regards to a system's life-cycle.

[minecrawler]

The new scheduler already caches stuff a lot. Even when changing to a different schedule, only previously unused systems will be initialized and then cached. This could be improved by offering an API to initialize a schedule at a user-defined time instead of when changing states. All in all, I get the feeling that changing states is a lot faster now and does not require calculations and pipeline-building anymore, so I'll close this in favor of more concrete improvements.