Add Spool command to cbq

Some RDBMS systems have a "spool" command that allow any data at the console to be written to a filename into the current working directory. For instance a spool command syntax could be like this:

sql> spool filename;
spool ON
sql> select sysdate from dual;

SYSDATE
---------
11-MAY-10
sql> spool off;
spool OFF

Inside the file would be :
sql> select sysdate from dual;

SYSDATE
---------
11-MAY-10
sql> spool off;