Emit comments in the .js and .d.ts files

This enables adding comments to the .js and .d.ts for all the declarations when --removeComments is not specified
Note the comments aren't correctly formatted and have extra spacing when they are multiline comment. That is a todo I am fixing separately.
Also handling of copyright comments will be separate pull request
Yes, it looks fine for leading comments, but I think you end up with an extra space character after a trailing comment.