Added GNU
revised flight modes
Added readme on the Sounds dir
Untested changes for arduplane
Corrected wav files naming for plane
Merge remote-tracking branch 'upstream/DisplayAPMPosition' into single-cell-lipo-voltage

Conflicts:
	Lua_Telemetry/DisplayApmPosition/SCRIPTS/Model_Name/telem1.lua
add math helper round, add info voice lipo cell-min, add play sound apm-messages.