Remove negation terms from the stopword list

[star1327p]

I noticed that the stopword list in English includes negation terms such as "no" and "not". These terms revert the meaning of a word or a sentence, so they should be preserved in the text data. For example, "not a good idea" would become "good idea" after stopword removal. Therefore, I recommend removing negation terms from the stopword list. Please also check if other languages (e.g. Spanish) have the same problem. Thanks!