pgsql: Add psql expanded auto mode

Add psql expanded auto mode

This adds the "auto" option to the \x command, which switches to the
expanded mode when the normal output would be wider than the screen.

reviewed by Noah Misch

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/95d2af1646080474ad3e1f1303e68dd5799f9cad

Modified Files
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doc/src/sgml/ref/psql-ref.sgml | 32 +++++++++++++++----------
src/bin/psql/command.c | 19 ++++++++++----
src/bin/psql/help.c | 4 +-
src/bin/psql/print.c | 51 +++++++++++++++++++++++++++++-----------
src/bin/psql/print.h | 4 +-
5 files changed, 73 insertions(+), 37 deletions(-)