Add -d option to pg_basebackup and pg_receivexlog, for connection string.

Without this, there's no way to pass arbitrary libpq connection parameters
to these applications. It's a bit strange that the option is called
-d/--dbname, when in fact you can *not* pass a database name in it, but it's
consistent with other client applications where a connection string is also
passed using -d.

Original patch by Amit Kapila, heavily modified by me.
Redo MSVC build implementation for pg_xlogdump.

The previous commit didn't work on MSVC editions earlier than
Visual Studio 2011, apparently. This works by copying files into the
contrib directory, and making provision to clean them up, which should
work on all editions.
Add -d/--dbname option to pg_dump.

You could already pass a database name just by passing it as the last
option, without -d. This is an alias for that, like the -d/--dbname option
in psql and many other client applications. For consistency.
Add -d option to pg_dumpall, for specifying a connection string.

Like with pg_basebackup and pg_receivexlog, it's a bit strange to call the
option -d/--dbname, when in fact you cannot pass a database name in it.

Original patch by Amit Kapila, heavily modified by me.
Only quote libpq connection string values that need quoting.

There's no harm in excessive quoting per se, but it makes the strings nicer
to read. The values can get quite unwieldy, when they're first quoted within
within single-quotes when included in the connection string, and then all
the single-quotes are escaped when the connection string is passed as a
shell argument.
doc: Fix markup typo