examples/ostest:  Works around a bug in printf() when cancellation points are enabled.  printf() is a cancellation point because it calls write().  This is correct according to OpenGroup.org.  However, printf holds the stdio library semaphore when it is canceled and this leaves the semaphore in a bad state.  No fix for the printf bug yet.

Add powerled driver example

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

examples/elf and nxff: Won't build with CONFIG_BUILD_KERNEL because the interface exec() is not available in that configuration.  Also, remove a stray comma and a stray semacolon in examples/pty_test/Kconfig and examples/random/Kconfig

apps/examples:  In elf and nxflat examples, remove low-level interfaces and replace with call to exec().

apps/examples/flowc: Fix some errors in receiver's verificationg logic.  Add a 'canned' data file so that we don't need to deal with the sender program; we can just 'cat' the canned data file.

nshlib/nsh_netcmds.c: Fix a compilation error when IPv4/IPv6 dual stack is enabled

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

    nshlib/nsh_parse.c: Avoid truncating the strcmp result into a unsigned char variable.

    nshlib/nsh_netcmds.c: Check for valid hostip before using it.

    nshlib/nsh_ddcmd.c: Fix resouce leak when 'if=' or 'of=' params are repeated in the command line.  For example:

       dd if=/dev/null if=/dev/zero of=/dev/null or
       dd if=/dev/zero of=/dev/zero of=/dev/null

    apps/examples/flowc:  Adds the necessary termios controls to enable hardware flow control

    apps/examples/flowc:  Add a simple test of serial hardware flow control.  This commit just defines the frame work.  Hardware flow control is not yet enabled.

    apps/netutils/netlib:  netlib_ipv[4|6]adaptor() will now use the new routing table interfaces if they are available:  If the desination IP address does not correspond to the network served by any device, then the address of the router that should get us to the correct sub-net is is determined.  Then the network adaptor that can communicate with the that router has the IP address that will returned.

    apps/netutils/netlib:  Add new utilities netlib_ipv[4|6]router() that can be used to determine the IP address of a router that would be used some some destination IP address that is not locally accessible.

    apps/netutils/netlib:  Add helpers for reading the routing table:  netlib_read_ipv4route() and netlib_read_ipv6route()

netlib_ipv[4|6]adaptor: Add a check to handle the case where the network device configuration changed asynchronously and the second IOCTL returns more data than the allocated buffer.

    netutils/netlib:  Add netlib_ipv6adaptor()
    netutils/netlib:  Add netlib_ipv4adaptor()

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>