Sentiment analysis for each message

[joweich]

Goal

Add a sentiment rating to each message in the parsed log. This should be done with libraries such as NLTK and VADER or Hugging Face's transformers.

Jobs to be done

• Create a new file nlp.py in chatminer
• Create a function def add_sentiment(df) to nlp.py, which adds the sentiment scores to the parser's output dataframe
• Adjust README with tutorial and example