* @class doc_renamesidref_common
 *
 * Replaces all uses of a given @c SIdRef type attribute value with another
 * value.
 *
 * @copydetails doc_what_is_sidref
 *
 * This method works by looking at all attributes and (if appropriate)
 * mathematical formulas in MathML content, comparing the referenced
 * identifiers to the value of @p oldid.  If any matches are found, the
 * matching values are replaced with @p newid.  The method does @em not
 * descend into child elements.
 *
 * @param oldid the old identifier
 * @param newid the new identifier