Langroid

RelevanceExtractorAgent: Handle segment-marking for text that has lost all/most punctuation, making it impossible to identify sentences.

LanceDocChatAgent: Handle empty query in query plan

DocxParsingConfig: add "python-docx" (previously only "unstructured" available)

* Fix windows logger issue 341
* OpenAIGPT local model detection, use "local/" not "local", and "litellm/" not "litellm" (comments in 346)

DocChatAgentConfig.filter_fields param: specify which fields are "filterable"

[DocChatAgentConfig](https://github.com/langroid/langroid/blob/main/langroid/agent/special/doc_chat_agent.py): new param
`add_fields_to_content`.

This lets you add additional fields into the "main" content field of a document. E.g. if a movie-related Document has fields `year`,
`genre`, `rating`, these can be added to the main `content` field,
as key=value pairs, e.g. year=1989, genre=Crime. (The original fields are left intact, so can still be used for filtering).
Adding fields to the content can help with retrieval since these would be taken into account when creating embeddings,
as well as during keyword/lexical search.
See test `test_doc_chat_add_content_fields` here: https://github.com/langroid/langroid/blob/main/tests/main/test_doc_chat_agent.py