Corrected writing to STDERR to not added line break
Upped retry handler for workers ready state. Shifted exception throw to after registering shutdown function
Updated signal test to make the child sleep longer so that dispatching a signal to the PID is more of a guarantee. Upped the tries counter on asserting a process is up, and allow for S+ process state.
Supervisor now maintains the correct number of workers and can increment and decrement them with the appropriate signals. Also decoupled the default worker closure to allow it to be specified now. RuntimeException is incurred if you attempt to start off a supervisor without a valid worker.
Updated PHPDoc and removed default parameter on run()