Add support for the BIT(N) column type #111

% sqlgg -<<'EOF'              
CREATE TABLE test ( X BIT(1) NOT NULL );
EOF
==> CREATE TABLE test ( X BIT(1) NOT NULL )
Position 1:25 Tokens: BIT(1) NOT NULL )
Error: Sqlgg.Sql_parser.MenhirBasics.Error
Errors encountered, no code generated