FTP: Adds support for IPv6 and fixes various transfer issues

* netutils/ftpd: Fix support for IPv6 FTP server

* netutils/ftpc:Adds support for IPv6 sockets

* ftpc: Must convert port received by EPSV reply to network order

* ftpc: Data socket address for passive connection should be same as server address

* ftpc: Must skip human readable string in EPSV response before scanning for port

* ftpc: Don't send PASS command if USER command was sufficient. ie no password required

* ftpc: Generically handle permanent negative completion in shard ftpc_cmd logic

* ftpc: Minor addresssing fix

* ftpc: Tweak logic for overriding network debugging output

* FTP: Adds option for setting stack size of various threads in FTPD and FTPC

* netutils/ftpd: Fixes build error setting IPv4 address. sin_addr => sin_addr.s_addr

* netutils/ftpd: Protects against partial write returns by looping in that case

Approved-by: Gregory Nutt <gnutt@nuttx.org>

apps/examples/ltdc:  Remove apps/examples/ltdc.  It violates the portable POSIX interface by calling directly into OS code.

smps, powerled examples: fix floating point format in printf

Approved-by: Gregory Nutt <gnutt@nuttx.org>

examples: add SMPS driver example

Approved-by: Gregory Nutt <gnutt@nuttx.org>

i8sak: Channel setting is now saved locally, so when performing a startpan or assoc, the channel previously set is still used, even though the MAC layer gets reset.  Also fixes a few build issues

Approved-by: Gregory Nutt <gnutt@nuttx.org>

include/netutils/netlib.h:  In order to avoid pre-processing warnings, NETLIB_SOCK_FAMILY must always be assigned a value, even if there is no real meaning value for it.

Fixed the compilation of nsh_routecmds.c, broken after commit 6b9d23c6



Approved-by: Gregory Nutt <gnutt@nuttx.org>

apps/fsutils/mkfatfs:  When fsutils/mkfats was split off from the operating system, there were a few dangling things left.  Some references to functions in the OS (which are not available in the protected and kernel modes) and several types and function prototeypes that don't exist is apps/fsutils/mkfatfs.

Adds i8shark, a sniffer "adapter" that captures all 802.15.4 traffic, packages it into a Wireshark ZEP packet, and sends it to a host running Wireshark.

Approved-by: Gregory Nutt <gnutt@nuttx.org>

i8sak: Changes 'notif' to 'primitive' corresponding to the changes in the Kernel

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Fixed misprint in cmd_wget

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Fixed i2ctool write operation in `no restart` mode (flag `-n`).

Approved-by: Gregory Nutt <gnutt@nuttx.org>

It seems that I2C driver has changed a bit since i2ctool was written,
so now i2ctool sends repeated start even if `no restart` flag (-n)
was passed to it.

include/netutils/netlib.h:  Add definitions needed when only local Unix domain sockets are supported.

Fix parsing of empty strings when CONFIG_NSH_CMDPARMS is not defined.  Problem noted by Juha Niskanen.

nshlib:  df command no long uses the non-standard OS interface foreach_mountpoint().  No simply cats /proc/fs/blocks or /proc/fs/usage.

nshlib:  mount command no long uses the non-standard OS interface foreach_mountpoint().  No simply cats /proc/fs/mount when there are no arguments to the mount command.

This commit removes the ping6 command from NSH and replaces it with the apps/system/ping6 built-in command.  The NSH ping6 command had to be removed because it violated the portable POSIX OS interface.  The apps/system/ping6 command uses the sem-standard IPPROTO_ICMP6 socket interface.

Squashed commit of the following:

    apps/system ping and ping6:  Fix a backward test.
    apps/system/ping6: ping6 logic now builds without error.
    apps/system/ping and ping6:  Minor clean-up to configuration settings.
    apps/system/ping6:  Minor clean-up to be able to configure CONFIG_SYSTEM_PING6
    apps/nshlib:  Remove support for ping6 from NSH.
    apps/system/ping6:  Add IPPROTO_ICMPv6 ping6.  Initial commit is simply a clone of the IPPROTO_ICMP ping logic.
    Rename CONFIG_NET_ICMPv6_PING to CONFIG_NET_ICMPv6_SOCKET.