This comment adds (1) basic support for AF_BLUETOOTH sockets. The logic compiles but is still incomplete. Support for Bluetooth is general is still dependent on CONFIG_EXPERMIMENTAL because it is not yet ready for used.

Squashed commit of the following:

    wireless/bluetooth:  Some small changes that gets to a clean compile by just eliminating some incorrect implementations (still with a lot of warnings.  The logic is still incomplete but now not so lethal.
    wireless/bluetooth:  Restructuring:  Connection interfaces should internal to wireless/bluetooth.  include/nuttx/wireless/bt_conn.h removed and merged with wireless/bluetooth/bt_conn.h.  Several fix to get closer to bt_netdev.c compiling.  Need to design some not interfaces and use some existing interfaces to send and receiv packets.
    wireless/bluetooth: Some organization with some network device compile errors fixed.  Still not even close to compiling.
    net/bluetooth:  Fix numerous compile issues; Still open design issues with regard to the interface with the Bluetooth stack.
    wireless/bluetooth:  Create bt_netdev.c with a crude copy of mac802154_netdev.c.  Does not not even compile yet.
    include/nuttx/net:  Add bluetooth.h.  Content is not yet correct.
    net/netpackets:  Add bluetooth.h.  Update net/bluetooth to use new socket address definition.
    net/bluetooth:  Some fixes for initial build.
    net/bluetooth:  Add initial support for Bluetooth sockets.  The initial cut is just the a clone of the IEEE 802.15.4 socket support with name changes.
    net/ieee802154:  Fix some typos noted when cloning to create net/bluetooth.

net/netdev/netdev_lladdrsize.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * net/netdev/netdev_lladdrsize.c
  *
- *   Copyright (C) 2017 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2017-2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -48,6 +48,7 @@
 #include <nuttx/net/net.h>
 #include <nuttx/net/netdev.h>
 #include <nuttx/net/radiodev.h>
+#include <nuttx/net/bluetooth.h>
 #include <nuttx/net/sixlowpan.h>
 
 #include "netdev/netdev.h"
@@ -62,7 +63,7 @@
  * Description:
  *   Returns the size of the node address associated with a packet radio.
  *   This is probably CONFIG_PKTRADIO_ADDRLEN but we cannot be sure in the
- *   case that there ar mutiple packet radios.  In that case, we have to
+ *   case that there are multiple packet radios.  In that case, we have to
  *   query the radio for its address length.
  *
  * Input Parameters:
@@ -127,6 +128,17 @@ int netdev_dev_lladdrsize(FAR struct net_driver_s *dev)
 #endif
 
 #ifdef CONFIG_NET_6LOWPAN
+#ifdef CONFIG_WIRELESS_BLUETOOTH
+      case NET_LL_BLUETOOTH:
+        {
+          /* 6LoWPAN can be configured to use either extended or short
+           * addressing.
+           */
+
+          return BLUETOOTH_HDRLEN;
+        }
+#endif /* CONFIG_WIRELESS_BLUETOOTH */
+
 #ifdef CONFIG_WIRELESS_IEEE802154
       case NET_LL_IEEE802154:
         {
@@ -140,7 +152,6 @@ int netdev_dev_lladdrsize(FAR struct net_driver_s *dev)
           return NET_6LOWPAN_SADDRSIZE;
 #endif
         }
-
 #endif /* CONFIG_WIRELESS_IEEE802154 */
 
 #ifdef CONFIG_WIRELESS_PKTRADIO