support the Google Gemini API

updated model lists

This adds a CLI tool to fetch some model data from @BerriAI/litellm

ask the rephrased question only if it has more context

Otherwise it's usually better to let the LLM reevaluate the context.

set custom info text for simulate sub command

emit the INDEXER_PAGE_ADD event

This allows plugins that add data to the fulltext index to add the same
data to the embeddings. This improves embedding searches with struct
data for example.

mechanisms to override things on command line

This should help with debugging/evaluating

automatic stylefixes

various refactoring and introduction of a simulate command

The new command makes it easier to run the same chat questions against
multiple models and compare the results in a spreadsheet