i8sak: Updates README to include details about socket interface and new addressing setup and fixes warning

* i8sak: Updates README to include details about socket interface and new addressing setup

* i8sak: Fixes warning about unitintialized variable

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

    Merged in merlin17/apps/i8sak-sock (pull request #108)

    i8sak: Fixes mistake where socket was accidentally bound to endpoint address
    i8sak: Fixes bad logic that bound outbound port to the destination address
    i8sak: Adds sniffer port option and a few other get/set parameters

    Merged in merlin17/apps/i8sak-sock (pull request #106)

    i8sak: Endpoint address is updated whenever 802.15.4 addressing information is updated
    wireless/ieee802154/i8sak: Converts PF_INETX to PF_INET6 and SOCK_IWPAN to SOCK_DGRAM
    wireless/ieee802154/i8sak: Catches case where arguments are included,  but the interface was never set
    wireless/ieee802154/i8sak: Endpoint IP address is now updated whenever 802.15.4 addressing info changes
    wireless/ieee802154/i8sak: Routes all error output to stderr rather than stdout

    Merged in merlin17/apps/i8sak-sock (pull request #104)

    i8sak: Fixes socket version of sniffer logic. socket logic for sniffer now works
    i8sak: Fixes socket version of sniffer logic. socket logic for sniffer now works

    Merged in merlin17/apps/i8sak-sock (pull request #103)

    wireless/ieee802154/i8sak: Adds socket interface support. You can now use both socket or char driver to control the MAC layer

    * wireless/ieee802154: Removes useless wpanlistener folder with build files
    * wireless/ieee802154/libmac: Merges some files together and adds some missing sixlowpan functionality
    * wireless/ieee802154/i8sak: Starts adding support for both character driver and socket
    * Removes unneccessary Kconfig statement
    * ieee802154: Adds function prototypes missed on previous commit
    * wireless/ieee802154/libmac: Fixes sixlowpan_resetreq
    * wireless/ieee802154/libmac: Small fixes and removes enableevents helper
    * apps/ieee802154/i8sak: Moves wpanlistener functionality into i8sak directly
    * apps/ieee802154/i8sak: Major restructuring to allow both char driver and socket control

        Also changes Kconfig options and certain args held previously by i8sak. This is to bring it closer to a real CLI tool rather than a development tool. For instance, no longer does the app change the addressing of the device automatically. This is because you probably don't want i8sak overwriting the extended address after board bring-up.  Additionally, the endpoint logic has been simplified.  There is only ever one active endpoint now.

    * wireless/ieee802154/i8sak: Non-functional clean-up.
    * i8sak: Removes chan and coordinfo commands and introduces generic get/set commands
    * i8sak: startpan now requires PAN ID argument
    * i8sak: Adds ability to set endpoint address using set command
    * i8sak: Minor fixes and cleanup
    * i8sak: Adds addrmode setting to i8sak. exposed via get/set calls
    * i8sak: Clean up poll logic and allow polling address mode to be based off endpoint address setting.
    * i8sak: Trivial
    * i8sak: Adds get/set hook for endpoint address mode (destination address mode)
    * i8sak:  Changes default address modes to short.
    * i8sak: Fixes build erros associated with enabling 6LoWPAN support
    * i8sak: Adds socket version of get/set implementation.  Simplifies some logic as well.
    * wireless/ieee802154/i8sak: Removes unused files
    * wireless/ieee802154/libmac: Fixes sixlowpan_assocresp.  resp was not being copied into the ioctl argument.

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

Added a simple reader example for the LIS3DSH acceleration sensor on STM32F4Discovery

* Added a simple reader example for the LIS3DSH acceleration sensor as
    found on STM32F4Discovery.

* Edited lis3dsh_reader_main.c to obey nuttx coding standard.

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

Rename CONFIG_AUDIO_DEVICES to CONFIG_DRIVERS_AUDIO to conform better to the evolving configuration naming standard.

examples/fb:  Add a simple test for the framebuffer character driver.  This initial commit just verfies some interfaces and initialization logic.  Still need to add to graphics update logic.

examples/adc: Fix g_adcstate.count initialization.

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

examples: add DAC example

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

apps/examples/nsh: Remove APPNAME, PRIORITY, and STACKSIZE settings from Makefile to avoid showing nsh in Builtin Apps.

dhcpd: Prevent buffer overflow in dhcpd_addoption.  offset represents distance from start of option buffer.  So this should be changed current option pointer minus start of buffer.

NSH:  Add conditions so that ifconfig and ifup will not be disabled if we are using only PF_IEEE802154

commit 6fbbca4ce308f5d8130d795342c7639555a7e5bf
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Sat Aug 19 08:46:27 2017 -0600

    apps/examples/pf_ieee802154:  Add PANID to command line options; Cannot bind to address zero... There is no counterpart to INADDR_ANY for these radios (not now at least).

commit 354111108a88f549248537e79dbf79998f458ded
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 17:47:10 2017 -0600

    PF_IEEE802154:  A few bugfixes

commit f1bb947609ed5e9e8816234653d6c8ee24585079
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 15:17:32 2017 -0600

    Add file missed in last commit

commit 9a73930e864db83609b5cc0d7c940d8efeaade66
Merge: 315b888f c433e07a
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 12:08:03 2017 -0600

    Merge remote-tracking branch 'origin/master' into pf_ieee802154

commit 315b888f4e72523d90b526edc5a82fb97678ff7e
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 12:06:51 2017 -0600

    examples/pf_ieee802154:  Add for testing PF_IEEE802154 sockets.

The last change added .PRECIOUS: $(BIN) to everyway Makefile in hopes the libapps.a will not be deleted on Control-C (unproven so far).  However, $(BIN) may contain back slashes in some build platforms and that causes problems for make:  It can't handle the backslashes in the .PRECIOUS dependency list.  $(BIN) replaced with ../../libapp.a, where the number of ../ depends on the depth of the Makefile in the apps/ source tree.

All Makefiles:  Add .PRECIOUS: apps/libapps.a to every Makefile.  Hopefully this will end awkward problems when you Control-C out of a build and libapps.a is deleted.

Application.mk:  Add the .PRECIOUS target to prevent libapps.a from being deleted when the make is interrupted.