carriage return is not removed from some command parameters

Although it is not recommended, it is allowed to have a carriage return in a qdoc command parameter that is enclosed in curly braces. qdoc is supposed to use QString::simplified() to sanitize the string so that all whitespace is replaced by a single ' '. But in at least one case, this didn't work, and the carriage return was left in the string, which caused qdoc to report that it couldn't find links that have the carriage return in them. The problem has been fixed by replacing the carriage return with a ' ' right when and where it is detected.