[conf] ins_float_invariant: simpler AHRS_*_FREQUENCY defaults
fix typos in CHANGELOG
[airborne] some minor style fixes
[fixedwing] rename LOW_BATTERY_KILL_DELAY to CATASTROPHIC_BAT_KILL_DELAY
[tmtc] gpsd2ivy: commandline options and verbose mode

- fix nan checks and warnings
- default to broadcast instead of multicast on linux
- make ivy_bus, gpsd server and port configurable via commandline
- added verbose mode which should help to track down issue #658