Release v5.4.0

• add isTruthy and isFalsy extensions for generic nullable types.
• Add immediateFirstRun option for DeBouncer to run the first call immediately.
• Global debouncer instance and debounce function for easy access to the debouncer.
• DeBouncer now allows returning a value from the debounced function in form of a Future<R> where R is the return
  type.
• Fix capitalized extension not working properly for strings with emojis.