Merge pull request #71 from pitr-ch/master

Add external event invoking and CancelablePolling actions
Fix the transactional adapter

+ some additional quick fixes
Merge pull request #82 from iNecas/fix-transactional-adapter

Fix the transactional adapter
Fix Executor#event to return Future object
Fix #81 - initialize things in right order in World

allow to pass Proc as a option value, which is lazy evaluated later with
World instance as argument