integrate range finder into fw landing
add missing $ in rcS script
Merge remote-tracking branch 'upstream/master' into fw_landing_rangefinder
set range finder to disabled as default
fw landing: do not use relative altitudes in TECS
fix comment for FW_LND_RFRALT
Merge pull request #744 from thomasgubler/fw_landing_rangefinder

Fw landing rangefinder