psql: Mention SSL protocol version in \conninfo.

Marko Kreen, reviewed by Wim Lewis.
libpq: Support TLS versions beyond TLSv1.

Per report from Jeffrey Walton, libpq has been accepting only TLSv1
exactly.  Along the lines of the backend code, libpq will now support
new versions as OpenSSL adds them.

Marko Kreen, reviewed by Wim Lewis.
Add recovery_target='immediate' option.

This allows ending recovery as a consistent state has been reached. Without
this, there was no easy way to e.g restore an online backup, without
replaying any extra WAL after the backup ended.

MauMau and me.
docs: mention CREATE TABLE LIKE linkage using INCLUDING DEFAULTS

Mention that CREATE TABLE LIKE INCLUDING DEFAULTS creates a link between
the original and new tables if a default function modifies the database,
like nextval().
Copy-editing docs for recovery_target='immediate', and "ie."

Phrase the sentence better. Also, spell "i.e." rather than "ie."

Thom Brown
Adjust C comment in slot_attisnull() regarding nulls.