Improve implementation of strategies for fork join pools
Add `DefaultForkJoinPool` as more suitable thread pool for actors than `DefaultExecutorService`
Add `Executor(execService: ExecutorService, batchSize: Long): Strategy` to allow fine tuning of trade off between fairness and throughput of actors
Reduce default batch size of actors from 1024 to 10 that allow to improve fairness of predefined Swing strategies
Fix the sequential strategy to run actors without stack overflow
Improve the naive strategy to minimize forking of new threads
Clean up of actor code and tests