ENG-5358: Prep work, delete DECIMAL_STRING, an ancient residue of the
first implementation of Decimal types in Volt.
ENG-5358: Add schema for the getTypeInfo() results table.
ENG-5358: Allow types to be specified as JDBC-visible or not, with all
types still not-visible.
ENG-5358: Use existing code for precision/radix.  Add JDBC values for
all JDBC-visible types.
ENG-5358: Move JDBC sql type discovery to VoltType.
ENG-5358: Add TYPEINFO selector to the JDBC database metadata
generator and wire everything up.
ENG-5358: Add a basic functionality test for getTypeInfo.
ENG-5358: Add SystemCatalog tests for TYPEINFO metadata.
ENG-5358: Make FLOAT/DOUBLE choice consistent.  Eliminate meta-data
method that can use results from VoltType.
ENG-5358: Everything is nullable, make that the default, reduce the
ENUM constructor arg set but leave the ability to tweak this in the
future.
ENG-5358: Push getTypePrecisionAndRadix to be a method on the the
VoltType object rather than static.
ENG-5358: Add some commentary
ENG-5358: Stop lying: we treat all SQL identifiers everywhere as UPPER
CASE.
Merge pull request #957 from VoltDB/eng5358

Eng5358, r=akhanzode