This PR primarily modifies the `cmm question --repeat` command to allow repeating multiple questions, instead of only the last one.
Additionally, this PR includes the following changes:
- In `ai_factory.py`, added optional parameters 'def_ai' and 'def_model' to the `create_ai` function which allows specifying a default AI and model.
- In `openai.py`, a potential bug was fixed where the 'tags' attribute was updated to ensure it is always a set, even when 'otags' is None.
- In `question.py`, a significant amount of new code was added to facilitate the 'repeat' functionality. This includes functions to create modified args based on an existing message (`create_msg_args`), to repeat a given list of messages (`repeat_messages`), and to invert the semantics of the INPUT tags for this command (`invert_input_tag_args`).
- In `main.py`, the 'nargs' parameter was changed from `+` to `*` in the 'or-tags', 'and-tags', and 'exclude-tags' arguments to accommodate the updated handling of tags in `question.py`.
- A new `test_common.py` file was added which includes a `FakeAI` class for testing purposes, and a `TestWithFakeAI` class which includes a number of methods for asserting various conditions about messages.
This PR also includes additional tests to verify the correct operation of the new 'repeat' functionality.
juk0de