Networking:  Clean up some naming that has bothered me for a long time... There are no interrupts and no interrupt handlers in the network.  There are events and event handler (there used to to be interrupt logic in there years ago but that is long, long gone).

Networking:  A placeholder for some missing logic in the previous change related to monitoring network status for dup'ed sockets.  If one of the dup'ed socket's is closed, then network monitor resources associated with that one socket must be recovered.  Also, in the event that socket is being used on one thread, but then closed on another, any threads waiting for events from the socket should be informed of the closure.  That latter requirement is not implemented because current data structures do not support it.

Networking:  Fix a runaway recursion problem introduced the previous fixe for shutting down dup'ed sockets.

Networking:  TCP disconnection callbacks are not retained in a list.  This will support mutiple callbacks per lower-level TCP connection structure.  That is necessary for the cae where a socket is dup'ed and shares the same lower-level connection structure.  NOTE:  There still needs to be a call to tcp_start_monitor() when the socket is dup'ed.

Networking:  Move two more TCP specific files from inet/ to tcp/.  There is other TCP-specific logic in inet/ that should be moved sometime, but those are more entangled.

Networking: Move net/inet/net_monitor.c to net/tcp/tcp_monitor.c in preparation for design change to fix monitoring of duplicated sockets.

6LoWPAN:  The original, Contiki-based design used only a single buffer for reassemblying larger packets.  This could be a problem issue for hub configurations which really need the capability concurrently reassemble multiple incoming streams concurrently.  These was also a design issue in that the reassembly buffer could be corrupted by outgoing packets.  The design was extended to support multiple reassembly buffers, each associated with the reassembly tag and source address.  This assures that there can be be no corruption of the reassembly once it has started.

Network procfs: procfs/net_procfs_route.c building error occur if CONFIG_NET_ROUTE is enabled.  Fix suggested by Aleksandr Kazantsev

PF_IEEE802154:  Improve some backlog counting logic; add more assertions to catch cases where the backlog count might deviate from the actual backlog.

PF_IEEE802154:  Add a maximum backlog option.  This will prevent overrun of the RX frame queue if many frames are received from the radio, but no application is receiving the queued data.

PF_IEEE802154: On input, there may be a list of frames provided, not just one.  When closed() and connection is freed, also need to free any frames remaining in the RX queue.

Networking:  Remove driver based backlog support.  This affects the entire network, but is used by only one driver.  The only supported with of supported RX backlog is via common read-ahead buffering.

commit 5b7b6e6e616c475c782e9883ada9f4a3b7cb4e2c
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Sun Aug 20 11:13:17 2017 -0600

    IEEE 802.15.4 network device:  Make same changes as per loopback device so that it will build with PF_IEEE802154 but without 6LoWPAN.

commit d656a98cf8eab2f20e884224b52cd47ec35df4cc
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Sun Aug 20 10:31:28 2017 -0600

    PF_IEEE802154: More fixes to device registration and to IEEE 802.15.4 loopback driver for PF_IEEE802154 without 6LoWPAN.

commit 866bb9cbb0c5af79734bbd434c07fa2560b6608f
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Sun Aug 20 09:58:13 2017 -0600

    Network: Reorganize some Kconfig selections.

commit 230b4cb48008cba5fccdafa22340df1d43584829
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Sun Aug 20 09:19:53 2017 -0600

    Changes to conditional compilation so that PF_IEEE802154 can build without 6LoWPAN

commit d96cbd6520d40590a740f695c4cd72208ce872da
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Sun Aug 20 09:17:02 2017 -0600

    configs/sim/pf_ieee802154: Disable 6LoWPAN, IPv6, TCP, and UDP.  Now things do not build

6LoWPAN/PF_IEEE802154:  Created radiodev.h and renamed various structures to provide a better separation between 6LoWPAN and PF_IEEE802154.

PF_IEEE802154:  With this commit PF_IEEE802154 address family is basically functional.  More testing is needed, of course.

commit 2a3ab1652a2c95bcfc8be8380fc7cbdcb6472938
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Sat Aug 19 08:44:31 2017 -0600

    PF_IEEE802154: Finish some missing bind() logic.  Add configs/sim configuration for testing.

commit 59be4b846a6e3bfe82087a888e3fdac9c3c414e5
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 19:30:04 2017 -0600

    PF_IEEE802154:  More renaming to decouple 6LoPAN from radios in general.

commit 69fabb1aea76e54381bdc13de28a3f1441fb42f4
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 19:21:11 2017 -0600

    PF_IEEE802154: Missed a few renamings.

commit ff0af1bb25567720934cc1c2a721ccd92cc35f89
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 17:46:58 2017 -0600

    PF_IEEE802154:  A few bugfixes

commit 01c7c84afd00cf907d280d30cfaf0fb2cf90e02e
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 17:01:31 2017 -0600

    PF_IEEE802154:  A few bugfixes

commit dcef4056d1c1488c93151135f3b7106977faa903
Author: Gre...

procfs routing table:  Don't print the IPv4 routing table header if the table is empty.  Fix a couple of places where CONFIG_NET_IPv4 was used wehre IPv6 was intended (not noticed now because I am testing with both enabled).

Network routing table:  Trivial name changes to make IPv4 and IPv6 more symmetric.  Add debug logic to dump the content of the router table.

Networking: Fix typo for 802.11 devices in netdev_register().  Was being masked before because depended on CONFIG_NET_MULTLINK.

Fix IPv6 loopback driver that depended on the removed g_ipv6_allonesaddr.  Noted by Masayuki Ishikawa