Re-apply ENG-4008 changeset.
Fix the sqlcoverage merge issue between the union and numeric functions changesets.
Merge branch 'master' into ENG-4008-retry
Remove as-yet-unused code for NValue::createDecimalFromDouble re: review feedback
Merge pull request #321 from VoltDB/ENG-4008-retry

Eng 4008 retry -- previously reviewed except for NValue.hpp