navigator: skip takeoff if already above takeoff altitude
mc_pos_control: trajectory following, using previous and next waypoints
mission: takeoff and next waypoint related fixes
mc_pos_control: navigation fixes, smooth position setpoint movements
Merge commit '2780dc39ce5d47f2d9dfa921062100a1dc86c2be' into mpc_track
mc_pos_control: reset position setpoint on entering to AUTO mode
mc_pos_control: move position offset limiting to separate method
Upgraded unit test framework
FTP: Add new open command for write.

All open commands now return file size.
FTP: Implement write command.
FTP: Add truncate command.

Unfortunately NuttX not provides truncate(),
had to be emulated by copying with O_TRUNC flag.
FTP: fix truncate errors. Also correct errno reporting.

Seems that warnx() everytime changes originak errno to EINVAL.
Merge branch 'master' into mpc_track
FTP: Rename command.

Payload: `<oldpath>\0<newpath>`
See: man 2 rename
FTP: Add file checksum calculation command.
navigator/mission.cpp: indentation fixed
Merge branch 'master' into takeoff_fix
mc_pos_control: commented code block removed
Merge branch 'master' into mpc_track
navigator: autocontinue fix