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.

snaga/postgres-xl,adam8157/gpdb,xinzweb/gpdb,oberstet/postgres-xl,postmind-net/postgres-xl,pavanvd/postgres-xl,techdragon/Postgres-XL,zeroae/postgres-xl,oberstet/postgres-xl,tpostgres-projects/tPostgres,ashwinstar/gpdb,kmjungersen/PostgresXL,lisakowen/gpdb,jmcatamney/gpdb,yazun/postgres-xl,Postgres-XL/Postgres-XL,tpostgres-projects/tPostgres,arcivanov/postgres-xl,tpostgres-projects/tPostgres,pavanvd/postgres-xl,adam8157/gpdb,jmcatamney/gpdb,pavanvd/postgres-xl,yazun/postgres-xl,jmcatamney/gpdb,xinzweb/gpdb,arcivanov/postgres-xl,50wu/gpdb,kmjungersen/PostgresXL,ashwinstar/gpdb,greenplum-db/gpdb,Postgres-XL/Postgres-XL,50wu/gpdb,ashwinstar/gpdb,snaga/postgres-xl,ashwinstar/gpdb,ovr/postgres-xl,lisakowen/gpdb,xinzweb/gpdb,pavanvd/postgres-xl,lisakowen/gpdb,xinzweb/gpdb,oberstet/postgres-xl,yazun/postgres-xl,kmjungersen/PostgresXL,oberstet/postgres-xl,ovr/postgres-xl,techdragon/Postgres-XL,greenplum-db/gpdb,arcivanov/postgres-xl,50wu/gpdb,zeroae/postgres-xl,adam8157/gpdb,techdragon/Postgres-XL,arcivanov/postgres-xl,postmind-net/postgres-xl,techdragon/Postgres-XL,zeroae/postgres-xl,zeroae/postgres-xl,ashwinstar/gpdb,adam8157/gpdb,arcivanov/postgres-xl,tpostgres-projects/tPostgres,Postgres-XL/Postgres-XL,yazun/postgres-xl,adam8157/gpdb,snaga/postgres-xl,techdragon/Postgres-XL,snaga/postgres-xl,zeroae/postgres-xl,postmind-net/postgres-xl,postmind-net/postgres-xl,50wu/gpdb,adam8157/gpdb,xinzweb/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,ovr/postgres-xl,oberstet/postgres-xl,50wu/gpdb,ovr/postgres-xl,ovr/postgres-xl,50wu/gpdb,xinzweb/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,adam8157/gpdb,jmcatamney/gpdb,arcivanov/postgres-xl,jmcatamney/gpdb,kmjungersen/PostgresXL,Postgres-XL/Postgres-XL,ashwinstar/gpdb,greenplum-db/gpdb,adam8157/gpdb,snaga/postgres-xl,xinzweb/gpdb,yazun/postgres-xl,lisakowen/gpdb,greenplum-db/gpdb,lisakowen/gpdb,greenplum-db/gpdb,lisakowen/gpdb,lisakowen/gpdb,50wu/gpdb,greenplum-db/gpdb,pavanvd/postgres-xl,kmjungersen/PostgresXL,tpostgres-projects/tPostgres,lisakowen/gpdb,postmind-net/postgres-xl,Postgres-XL/Postgres-XL,50wu/gpdb,jmcatamney/gpdb,xinzweb/gpdb