Add test coverage for UPDATE with inline varchar being assigned to outlined varchar
Add testing for CAST, CASE WHEN with inline VARCHAR columns
Make NValue::serializeToTupleStorage not throw an exception when asked to allocate from inlined data, allocate in temporary string pool instead
Don't call getTempStringPool unconditionally...cpp tests do not cooperate.
Update sql_coverage with minimal changes to exercise inlined varchar columns
Merge pull request #1628 from VoltDB/ENG-6666-set-nvalue-no-throw

Make setNValue allocate objects in temporary string pool, if needed