[build] Use g++ by default now for building.  Fix a few casting issues on the Pi's c++ build.
[channelout] Add RF24 submodule for direct output of Komby nRF data.
[channelout] Initial work for Komby nRF output from the Pi

Note: there may be bugs and TODOs left, but pretty much ready to go.
Tested both direct file playback and bridge mode, but I have not done
any timing tests on how long it takes to write to SPI, nor checked
maximum channel outputs.
Merge branch 'nrf_output'

Conflicts:
	src/Makefile
	src/channeloutput/FPD.c
	src/channeloutput/channeloutput.c
	src/settings.c

Conflict Notes:
	src/Makefile - context lines around new library changed to cleanup
	the auto-generated fppversion.c file.

	src/channeloutput/FPD.c - fix for g++ compile in a line that was
	removed on master no longer needed.

	src/channeloutput/channeloutput.c - header includes added on both
	branches, LOR on master, and nRF on branch.

	src/settings.c - another g++ fix that was in some code that was
	changed on master for the memory used for our fppDirectory setting.
Merge branch 'master' of https://github.com/FalconChristmas/fpp
[build] Put our deps first and make sure the git submodule is initialized before we build fppd's objects