Improve comment-region and uncomment-region

[cjohansson]

Sometimes the result is not what you expect

[cjohansson]

I think it would be better if the comment / uncomment functionality would be based on the lexer tokens

• Comment / uncomment line if only one entire line is marked
• Comment / uncomment lines if multiple entire lines are marked
• Comment / uncomment region if not entire lines are marked

[cjohansson]

Fixed in this commit