PHP 5.5 deprecates preg_replace /e modifier

Updated where preg_replace() was used with the /e modifier to instead use preg_replace_callback().

Changes to RetrieveFM7VerboseData.class.php have been tested and are working for me.

Changes to RetrieveFMXML.class.php (other than removing the 'e' from items in $UTF8SpecialChars) I'm not exactly sure how to test, but it's not giving me errors.
Considering that RetrieveFM7VerboseData is a descendant of RetrieveFMXML, I think it would be better to simply call the function that lives there.