added PyAudio instantiation status variable and related comments
refactored instantiate() to setup()
added duplicated setup avoidance
completed logic for variable instantiate within setup()
introduced run.py
privatized findHostAPI() and findDevice()
added frame_per_buffer parameter to config.py
refactored variable frame_per_buffer to frames_per_buffer
added __start_stream() private function and associated callback function callback()
changed stream start to True by default