XTCE13 — CustomAlarmType has wrong parent

The CustomAlarmType appears to extend BaseAlarmType, where as it should just be an extension of InputAlgorithmType (or similar). The result is there are three name attributes to fill in if you want to do so.

In fact because the AlarmType is the base for all the various DefaultAlarms, the CustomAlarm should probably extend a stubby version of InputAlgorithm without a name or description attribute.