Whitespace
Test for #43

Assert that all subscribers are called, even if some are unsubscribed during publishing
Fix for #43

Refactor the internals to not use arrays, so we are free to modify the list of subscribers without causing problems.
Fix linting
Merge pull request #44 from mroderick/43-call-all-subscribers-despite-unsubscription

#43 call all subscribers despite unsubscription