Reads rest of comment (starting '[' already input) and acts accordingly.
If comment is an output comment, and if an output stream has been attached, writes the output comment to the output stream. Otherwise, output comments are simply ignored like regular comments. If the labileFlag bit saveCommandComments is in effect, and we are NOT in the middle of a token then the comment (without the  braces) will be stored in token. All other comments are stored as embeddedComments. Returns true if a command comment was read and stored as the token