pg_restore recognizing $-quotes

Not sure if this is the desired approach, but since it works, I thought I'd
send it.

This patch allows pg_restore to recognize $-quotes in SQL queries. It will
treat any unquoted string that starts with a $ and has no preceding
identifier chars as a potential $-quote tag, it then makes sure that the
tag chars are valid. If so, it processes the $-quote.

Tested against local DBs and regression DB.

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Philip Warner | __---_____
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and from pgp.mit.edu:11371 |/