add method
Adds a new state with the given ID to the state machine.
Implementation
StateMachine add(String id, State? state ) {//State?
if ( state is State ) {
states[id] = state;
}
else {
yukaConsole.warning( 'YUKA.StateMachine: .add() needs a parameter of type "YUKA.State".' );
}
return this;
}