Realtimetts

- merged 22 & fixed 23 (thank you)
- change CoquiEngine cloning_reference_wav parameter to "voice"
- added coqui predefined [speaker voices](https://github.com/KoljaB/RealtimeTTS/tree/master/tests/coqui_voices)
Submit name or parts of the name as voice (case-insensitive):
python
engine = CoquiEngine(voice="aaron")

RealtimeTTS will first look for wav or json files, then for the predefined speaker voices

- support for multiple speaker cloning reference wave files of coqui engine (submit them as list of filenames as you normally would with a single filename string)
- default voice now male (female voice [here](https://github.com/KoljaB/RealtimeTTS/blob/master/tests/female.json))

- bugfix: AIFF system voice synthesis generation under Mac caused Exception
- bugfix: "muted" parameter together with Elevenlabs caused Exception

- play methods got muted parameter
If True, disables audio playback via local speakers (in case you want to synthesize to file or process audio chunks). Default is False.
- CoquiEngine got a set_speed method to change at runtime

- fixes 17, 18

- support of [openai tts engine](https://github.com/KoljaB/RealtimeTTS/blob/master/tests/openaitts_test.py)