Add convenience function to supply a EventDataRef to Event::signal()
Rewrite our callback dispatcher. Instead of dynamically create new
threads for each callback they are now precreated when they are
registered. Each callback will now be called using the same thread each
time.
Remove old code
Remove debug code
Made the loop a bit smaller
There is no need for Event::signal(EventData *) to be virtual. It is not subclassed anywhere
Merge branch 'callbackdispatcher-rewrite'