Update schematron to check for "other" attribute co-occurrence

[rockivist]

Schematron should check that the following co-occur:

@physdescstructuredtype="otherphysdescstructuredtype" / @otherphysdescstructuredtype

@daotype="otherdaotype" / @otherdaotype

@dsctype="otherdsctype" / @otherdsctype

@relationtype="otherrelationtype" / @otherrelationtype

@level="otherlevel" / @otherlevel

[tcatapano]

Implemented. Closed.