Mission Planner - Simulation

#### Issue details
In simulation, they SITL (plane/plane) starts up in Australia (CMAC) even when --home= is set in the Simulation tab

#### Version
_What version was the issue encountered with_
Mission Planner 1.3.74.1 Build 1.3.7701.34374

Windows 10
[ ] All
[ ] AntennaTracker
[ ] Copter
[x ] Plane Simulation
[ ] Rover
[ ] Sub

#### Airframe type
plane

#### Hardware type
SITL

#### Logs
_Please provide a link to any relevant logs that show the issue_

Reproduce a Plane SITL simulation on Windows 10 using Mission Planner 1.3.74.1, setting --home= in the Simulation tab, and confirm whether it starts at CMAC in Australia. Trace the Simulation tab's handling of the --home= value; done when the configured home location is used instead of the default location.

Written by the indexing model from the issue text.