Version 3.3.0

Major changes since 3.2.1:

• Possible backward incompatibility: if PyAudio is not installed, Microphone now throws an AttributeError when created rather than not being defined.
  • This only requires changes if you are explicitly testing for the existance of the class, using something like hasattr or getattr.
• More robust error handling - always clean up PyAudio resources, no matter what error conditions arise.
• Better error checking - always verify PyAudio version.