Changes

Code was not wrapped in a try-catch block
` visit(OWLSubClassOfAxiom axiom)` uses a try-catch block to call
`notSupported()` if a `UnsupportedICException` is thrown.
 The same mechanism was _not_ used in `visit(OWLDataPropertyRangeAxiom
axiom)`, so the code never got to `notSupported()`, resulting in a
`UnsupportedICException` bubbling up instead of simply generating a
warning.
 (commit: b9b054c)