Log Message:
update to 4.7.4
changes:
-any class with a count() method now supports the len() builtin
-added the missing == and != operators to QItemSelection
-added readQVariantHash(), readQVariantList(), readQVariantMap,
 writeQVariantHash(), writeQVariantList() and writeQVariantMap()
 to QDataStream
-added the ErrorPageExtensionOption and ErrorPageExtensionReturn classes,
 and the ErrorDomain enum to QWebPage