[CLEANUP] tidy up addContextConstraint a bit, accidental import
[MONDRIAN-1861] workaround: avoid native execution for disjoint compound slicer

had put a trivially wrong result in testSlicerTuplesPartialCrossJoin
temporarily using the placeholder as an all-purpose placeholder
[MONDRIAN-1861] nativize slicer tuples when disjoint or multilevel

main change: SqlConstraintUtils.addContextConstraintTuples
only using when detected disjoint or uneven levels
added slicer tuple to native constraint key
still using placeholder
some accidental indentation changes
[MONDRIAN-1861] use evaluator instead of placeholder (merge last commit)

also, using optimizedSlicerTuples now
[MONDRIAN-1861] minor clean in SqlConstraintUtils
[MONDRIAN-1861] enable multivalue in expressions for vertica

for more compact slicer tuple constraints
Merge pull request #37 from tgf/nativeTuplesSlicerMerge

Native tuples slicer merge