Debug/NuttX: small changes to make it work with the current stable branch. Debug/NuttX made existing code work with python3 in gdb. Added some new features

sdlog2_dump.py: minor fix

Increase GPS position timeout to real-life timeouts. More work needed.

Mavlink: don't use mavlink helpers

Airspeed filtering, reinstate TECS for testing

Differentiate between EPH and  EPV. Do not declare position invalid because of EPV (because we use the baro anyway). No fundamental logic change / cleanup to ensure current approach and arming logic remains intact

fetch_log.py renamed to fetch_file.py and reworked

fetch_log.py renamed to fetch_file.py and reworked, works with all files, not only logs, added recursive directory download

nshterm: increase stack size to fix crash on 'ls -l'

Improve update performance and clean compiler warnings in px4io driver

Mavlink onboard

Improve user feedback on mission load fails

This reverts commit 503ded05.

Conflicts:
	mavlink/include/mavlink/v1.0
	src/modules/fw_pos_control_l1/fw_pos_control_l1_main.cpp

This reverts commit ce78b399.

Conflicts:
	src/modules/fw_pos_control_l1/fw_pos_control_l1_main.cpp
	src/modules/fw_pos_control_l1/fw_pos_control_l1_params.c