Squashed commit of the following:

commit 2dc03630a736be2ae9f64823aabb5776e7074c2a
Merge: 61e325c 0da552c3
Author: Bruce A. Mah <bmah@es.net>
Date:   Thu May 26 09:40:58 2016 -0700

    Merge branch 'master' into issue-325

commit 61e325c5d0a4e7a9823221ce507db0f478fc98b5
Merge: 227992f ccbcee6
Author: Bruce A. Mah <bmah@es.net>
Date:   Thu May 26 11:09:54 2016 -0400

    Merge branch 'issue-325' of github.com:esnet/iperf into issue-325

    Conflicts:
    	src/iperf3.1

commit 227992f366e7f4895b6762011576ba22a42a752e
Author: Bruce A. Mah <bmah@es.net>
Date:   Thu May 26 11:07:01 2016 -0400

    Don't set SO_MAX_PACING_RATE if the rate is 0.  Also tweak some help text.

    Towards #325, in response to feedback from @bltierney.

commit ccbcee6366d50ec632fc00eb11fde8a886f8febe
Author: Bruce A. Mah <bmah@es.net>
Date:   Tue May 24 09:19:41 2016 -0700

    Fix manpage formatting for consistency.

commit 90ac5a9ce09bd746ca5f943a8226ab864da3ebf8
Author: Bruce A. Mah <bmah@es.net>
Date:   Tue May 24 12:14:16 2016 -0400

    Add some documentation for fair-queueing per-socket pacing.

    For #325.

commit 5571059870f7aefefb574816de70b6406848888f
Author: Bruce A. Mah <bmah@es.net>
Date:   Tue May 24 11:55:44 2016 -0400

    Change the fair-queueing socket pacing logic in response to feedback.

    By default, on platforms where per-socket pacing is available, it
    will be used.  If not available, iperf3 will fall back to application-
    level pacing.

    The --no-fq-socket-pacing option can be used to forcibly disable
    fair-queueing per-socket pacing.  (The earlier --socket-pacing option
    has been removed.)

    Tested on CentOS 7, more testing on other platforms is required to
    be sure it didn't break the old application-level pacing behavior.

    For #325.

commit 3e3f506fe9f375a5771c9e3ddfe8677c1a7146e7
Merge: 50a379e 3b231126
Author: Bruce A. Mah <bmah@es.net>
Date:   Tue May 24 09:54:39 2016 -0400

    Merge branch 'master' into issue-325

commit 50a379eddfa89d1313d2aeeb62a6fbc82f00ea17
Author: Bruce A. Mah <bmah@es.net>
Date:   Sat Apr 16 02:55:42 2016 -0400

    Regen.

commit 200d3fe3917b3d298bdf52a0bde32c47cf2727b0
Author: Bruce A. Mah <bmah@es.net>
Date:   Sat Apr 16 02:41:32 2016 -0400

    Checkpoint for initial work on #325 to add socket pacing.

    This works only on Linux and depends on the availability of
    the SO_MAX_PACING_RATE socket option and the fq queue discipline.
    Use --socket-pacing to use SO_MAX_PACING_RATE instead of the
    default iperf3 user-level rate limiting; in either case, the
    --bandwidth parameter controls the desired rate.

    Lightly tested with both --tcp and --udp, normal and --reverse.
    Real testing requires analysis of packet timestamps between
    multiple hosts.