Banterbot

Two new characters have been added, Henri the French teacher, and Chen Lao Shi the Mandarin Chinese teacher

The TKinter UI has been updated and the reliability of speech synthesis has been improved, especially after an interruption. Efficiency improvements have also been made.

A lot of changes have been made to the way data is handled from the OpenAI API and Azure Speech API, and a number of optimizations have been made to some other parts of the backend, including some parts that are now using numba's JIT compilation for improved performance.

This new update includes improved CLI functionality: in addition to the existing command `banterbot`, you can now run subcommands `banterbot character [charactername]` to initialize a preloaded character, and `banterbot voice-search [params]` to search through all the available neural voices by gender, country, language, and region to find the right voice for your BanterBot. Neural voices are now connected directly to the Azure Speech SDK, meaning it is always up to date.

This update consists of a major code refactoring and a number of minor but helpful optimizations

Classes Interface and SpeechToText have been reworked to improves responsiveness on user voice input, and now works much more smoothly and reliably.