This could happen and then the sleep duration would wrap and be huge.

this will be needed for fast replay. In addition, this option disables
the orb interval.
It can be removed again once we have time simulation.

when doing fast replay, hrt_absolute_time() will not match the replayed time
thus we just use the same timestamp as the input sensors.

so that CI will build it

if a parameter name was 16 characters long (which is valid), the last
character got truncated due to 0-terminated string.
This raises the param name to 64 chars, which is quite wasteful, but there
is no other length in between.

vehicle_status_flags_pub passed to publish_status_flags() was always null,
thus orb_advertise() was called each time.

Note that it did not produce a memory leak.

currently jmavsim uses a default rate of 500 Hz which is too much.

In hil mode, sensors is responsible for publishing this topic.

This makes sure no sensor publishes sensor topics, instead they will be
published from mavlink.

This does the following if given:
- don't initialize the sensors (the sensor drivers are not started)
- publish sensor_combined even in hil mode
- do not apply or publish thermal corrections

in HIL mode, gyros are published after mc_att_control started.

land_detector: delete unused class enum

mc_pos_control: delete spaces

mc_pos_control: cleanup and threshold for velocity control to altitude control when close to max altitude

The previous implementation returned OK when the sensor was not calibrated and vice
versa. This fixes a preflight fail due to selftest failed.

 - closes #6686
 - closes #6294

This flag is triggered when the manual kill switch is activated. The motors
did not stop when the kill switch was engaged before adding this check.

In order to use px_uploader as a module from another Python script, all
the action needs to be moved into a main() function which is only called
if the file is run directly.

Sometimes right after reboot, we got a `raise SerialException(
msg.errno, "could not open port {}: {}".format(self._port, msg))`.
If this happens now, we will just try again later.

Found by PEP8 checker.