Twitterbot

This package was woefully out of date. It has been updated to use python 3.7 and current versions of python packages.

It was still possible to get into a state where the bot would reply to itself. That has been fixed.

There was a bug in the message tokenizer which caused it to break tweets before it had to. It now uses as much of the 140 characters as possible

Major features in this release
- New built-in message provider, MarkovChainMessageProvider, which creates random messages based on provided text.
- New built-in since_id provider, RedisSinceIdProvider, which stores the since_id in redis

There has also been several API changes:
- There are now base classes for message and since_id providers, BaseMessageProvider and BaseSinceIdProvider
- A new parameter, max_message_length, is required on the MessageProvider create method: def create(self, mention, max_message_length)

There was a bug in replying to mentions where the bot would include its own name, triggering another reply including its own name, and so on.

Settings file can now take either a class or a string to specify providers.
Message provider .create() function now takes the mention info.