Default conversion between QVariant and QtScript Object

Currently, if you call QScriptValue::toVariant() on an Array object, you get back a QVariant containing a QScriptValue containing the array, i.e. an opaque QVariant. Perhaps Qt Script could convert the Array to a QVariantList instead; this would be more useful. Similarly, a plain object could be converted to a QVariantMap. qScriptValueFromValue() should do the conversion the other way.