classRef when @expand not specified is inconsistently translated to RNG

[lb42]

A classRef with no value for its @expand attribute appears to generate different results depending on what other attributes are present. If no other attributes are present, the classRef generates a pattern matching the alternation of its members. If @include or @except is present, a pattern matching the sequence of its members (after applying inclusion or excepting as expected) is generated. For evidence see the testClass odd supplied on issue 220.

[hcayless]

See #220 for test ODD.

@except also does not work the way I would expect unless the excluded element is a direct member of the referenced class. If the element is a member of a sub-class of the referenced class, weird (invalid) things happen instead.