Improve arty and statics

[rekterakathom]

When merged this pull request will: Title

1. Describe what this pull request will do Improve logic relating to disembarking artillery and static weapons.

2. Each change in a separate line

   • Disembark only the crew (sometimes mission makers group up all statics, so don't disembark the whole group)

• Remove distanceSqr optimization for readability

• Remove useless _static variable

• Apply suppression to all crew of the vehicle when disembarking (some static weapons have multiple units in them)

• Don't call doVehicleSuppress after disembark (wasn't a huge issue but it was probably unintended)