If a table column name begins with "__hidden__" then do not include that

If a table column name begins with "__hidden__" then do not include that
column in "*" expansions in SELECT statements, nor fill in that column in
an INSERT INTO that omits the column list.  <b>This branch is a
proof-of-concept only and is not intended to ever be merged into trunk.</b>

FossilOrigin-Name: 2dbffb3a3b20dba7d7d86c8ad2e34633f616c78a