- the behavior of String/Unicode types regarding that they auto-convert

- the behavior of String/Unicode types regarding that they auto-convert
  to TEXT/CLOB when no length is present now occurs *only* for an exact type
  of String or Unicode with no arguments.  If you use VARCHAR or NCHAR
  (subclasses of String/Unicode) with no length, they will be interpreted
  by the dialect as VARCHAR/NCHAR; no "magic" conversion happens there.
  This is less surprising behavior and in particular this helps Oracle keep
  string-based bind parameters as VARCHARs and not CLOBs [ticket:793].