Networking:  Replace all references to net_ipaddr_t with either in_addr_t on net_ipv6addr_t.  The goal is to support both IPv4 and IPv6 simultaneously.  This requires that the two types be distinct and not conditionally typedef'ed to net_ipaddr_t.

This is not the official configuration for the PX4 board and has led to confusion by NuttX users.  The board configuration also requires some ongoing maintenance and customization to support ongoing PX4 testing and evaluation.  It is best retained the PX4 repositories where it can be properly maintained and not in the upstream NuttX repository.

Signed-off-by: Marco Krahl <ocram.lhark@gmail.com>

apps/system/composite:  Fix some corrupted conditional compilation that crept in.  Looks like some automatated update gone awry.

apps/system/usbmsc:  Fix some corrupted conditional compilation that crept in.  Looks like some automatated update gone awry.

STM32 LTDC: Move ltdc.h from include/nuttx/video to arch/arm/include/stm32; Trivial updates after general review

Signed-off-by: Marco Krahl <ocram.lhark@gmail.com>

Add basic board support for the DK-TM4C129X Connected Development Kit.  The initial commit is simply the TM4C123G Launchpad with naming changes