Make pg_dump output more portable and more pleasing to look at.

The -n and -N options were removed.  Quoting is now smart enough to
supply quotes if and only if necessary.

Numerical types are now printed without quotes, except in cases of
special values such as NaN.

Boolean values printed as true and false.

Most string literals now do not escape whitespace characters (newlines,
etc.) for portability.

SET SESSION AUTHORIZATION argument is a string literal, to follow SQL.

Made commands output by pg_dump use consistent spacing and indentation.