GPS issues

**Details**
GPS issues
Change mode - ALT_HOLD and LOITER

**Comands**
*Stabilization*
mavgraph.py GPS_issues1.BIN "ATT.DesPitch" "ATT.Pitch" --flightmode=apm
mavgraph.py GPS_issues1.BIN "ATT.DesRoll" "ATT.Roll" --flightmode=apm

*GPS*
mavgraph.py GPS_issues1.BIN "GPS.Lat" "GPS.Lng" --flightmode=apm

*Altitude measurements*
mavgraph.py GPS_issues1.BIN "CTUN.BarAlt" "CTUN.Alt" "CTUN.DAlt" --flightmode=apm