Testing the mode "Altitude hold". Different altitudes

**Details:**
GPS not connected
Take off -> stabilize mode
Land -> altitude hold mode
good IMUs
good landing
antivibration platform
Altitude issues

**Commands**:
 *Stabilization*:
 mavgraph.py ALT_HOLD_test1.BIN "ATT.DesPitch" "ATT.Pitch" --flightmode=apm 
mavgraph.py ALT_HOLD_test1.BIN "ATT.DesRoll" "ATT.Roll" --flightmode=apm

*IMU:* 
mavgraph.py ALT_HOLD_test1.BIN "IMU.AccX" "IMU.AccY" "IMU.AccZ" --flightmode=apm

*Altitude measurements*: 
mavgraph.py ALT_HOLD_test1.BIN "CTUN.BarAlt" "CTUN.Alt" "CTUN.DAlt" --flightmode=apm