[MONDRIAN-1694]  Since a native filter can be used even when the context is not NON EMPTY, the cache key needs to include NON EMPTY state.  Otherwise the resulting tuple
list may not correctly reflect isNonEmpty.
Merge pull request #201 from mkambol/mon1694

[MONDRIAN-1694]  Since a native filter can be used even when the context...
[MONDRIAN-1825] Fixed issue with case statements used in sets, the return
type was evaluating the first param vs. the first return param.