Support schema prefixing

[tschf]

e.g.

sys.dbms_output.put_line
--or
dbms_output.put_line

[bjshumway]

I thought that I had solved this issue, but I did not. I thought sys was the prefix for standard functions (e.g. ... sys.trunc), but this is not true. The example Trent gives above shows that sys is a prefix for common oracle packages.