Bump down extra_float_digits to 2

This is to avoid breaking 8.4 in preparation for fully supporting it
in an upcoming patch (see #199).

Note that the tests here do not correctly check for a required
extra_float_digits=3, since they still pass; this should be
reviewed further.
Send bytea values in "escape" format to old servers
Don't look at AffectedRows in SELECT for pre-9.0 servers

It looks like the number of rows affected by SELECT was not part of
the command tag before version 9.0, though I can't see a mention of
it in the release notes.
Don't try to run TestByteaOutputFormats against old servers
Remove usage of DO in test cases
Add tests for 8.4
Adding Hstore support package
Add Jeremy Jay to Contributors
Try to infer the time zone for timestamptzs from TimeZone

When receiving a "timestamp with time zone" value from the database
we try to set its time zone based on the current value of TimeZone.
If, and only if, the offset we got from the local time zone database
matches the offset we got from the server, we return the new value
with time zone information.  This way the user always gets the time
as the database sent it (even if the local database is not in sync
with the remote one), which maintains backwards compatibility and
avoids confusion.

This should currently work correctly in all cases, but if we ever
start supporting multiple simultaneous queries, we will have to be
careful to use the correct TimeZone value for each of them.
Add test cases encoding in both output formats
Use t.Errorf instead of t.Println

Silly thinko in 4c2445c5c31b5098f6d8355036.
Note hstore support; in-progress LISTEN/NOTIFY support
Add support for bulk imports with COPY FROM STDIN

 * db.Prepare("COPY foo (a, b) FROM STDIN") returns a COPY IN
   statement
 * stmt.Exec(a, b) inserts new items
 * stmt.Exec() syncs the input stream, since sql.Stmt.Close() does not
   return errors from stmt.Close()
Add Oliver Tonnhofer to Contributors; update Features/Future
Fix 8.4 COPY

This respects the bytea encoding format for 8.4 when using COPY.
Process bytea through proper escaping

This actually fixes COPY on 8.4
Test Queryer as well as Execer
Send bytea in the correct format in all cases

I failed to spot this case in 6a22d6803c4697d6177a54c379f8d3de56,
which means that we don't have automated tests for that case.  Add
them as well.
Revert "Test Queryer as well as Execer"

Queryer wasn't present in Go 1.0, so we can't try and run this test
there, at least not as written.  Reverting for now.

This reverts commit de28fd30151bcc4bc7833c82d59051c443cee3aa.
Clarify comments in parseBytea