Slightly safer way to handle a possible exception when calling a listener.
This way if an exception is thrown providing the task to the executor, we will still call the other listeners.
Added @since documentation for things that were added in 1.2.0
Added @since annotations for all inner classes (and for their correct insertion date)
Added a "SameThread" executor implementation.
It was almost an oversight that we had not included this earlier.  It is different from the "NoThreadScheduler" as everything provided to it is executed immediately (instead of waiting for the next call to .tick)
More unit test verification around this simple wrapper (but still worth having)