pgsql: Update examples for string-related functions.

Update examples for string-related functions.

In the example for decode(), show the bytea result in hex format,
since that's now the default.  Use an E'' string in the example for
quote_literal(), so that it works regardless of the
standard_conforming_strings setting.  On the functions-for-binary-strings
page, leave the examples as-is for readability, but add a note pointing out
that they are shown in escape format.  Per comments from Thom Brown.

Also, improve the description for encode() and decode() a tad.

Backpatch to 9.0, where bytea_output was introduced.

Branch
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REL9_1_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/3e80d0d2e5a0f6a7a971ddcb6e38cc8f0079aed7

Modified Files
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doc/src/sgml/func.sgml |   26 +++++++++++++++++---------
1 files changed, 17 insertions(+), 9 deletions(-)