some improvements
improved process decorator
more improvements to decorators
big refactoring: code reorganization, added more tests, fixed Python3 process pool hanging bug, no more polling in decorator functions
small code cleanup
moved pools' common logic in separate module
windows fixes and more unittests
update setup packages
merge branch dec_impro
release 2.4.9: refactored decorators, changed project layout for better maintainability, improved decorators and pools performance and stability, improve tests