func (eventManager *EventManager) RunKeyEvent(key Key, action Action) {
	for i := range eventManager.Objects {
		if val, ok := eventManager.Objects[i].(KeyboardEventResponder); ok {
			val.OnKeyboard(key, action)
		}
	}
}
RunKeyEvent simulates a key event, triggering the expected response from
the EventManager's objects.
package paunch
type EventManager struct {
	Objects []interface{}
}
func NewEventManager() *EventManager {
	return &EventManager{make([]interface{}, 0)}
}