This replaces *Conn.CopyTo. CopyTo was named incorrectly. In PostgreSQL
COPY FROM is the command that copies from the client to the server. In
addition, CopyTo does not accept a schema qualified table name. This
commit introduces the Identifier type which handles multi-part names and
correctly quotes/sanitizes them. The new CopyFrom method uses this
Identifier type.
Conn.CopyTo is deprecated.
refs #243 and #190
Jack Christensen