disable -Werror
add xbee library folder for linux
Merge pull request #466 from thomasgubler/disable_Werror

disable -Werror
Merge pull request #467 from thomasgubler/linux_xbee

add xbee library folder for linux
Fix -Wunused-variable -Wunused-function -Wunused-but-set-variable
Fix -Wunused-local-typedefs
Fix /Wd4702 unreachable code
Turn off overrides for fixed warnings
Merge branch 'MoreWarnings' of https://github.com/DonLakeFlyer/qgroundcontrol into MoreWarnings