Ensure object position is valid before distance calc

fix gauges racing condition

fix co_pilot management form

fixed co_pilot selection list

improved driver variable management

fix NaN on rotation

check for NaN values

Merge pull request #79 from farribeiro/patch-27

Merge pull request #78 from farribeiro/patch-26

Merge pull request #77 from farribeiro/patch-25

Merge pull request #76 from farribeiro/patch-24

Merge pull request #75 from farribeiro/patch-23

Merge pull request #74 from farribeiro/patch-22

Merge pull request #73 from farribeiro/patch-21

Merge pull request #72 from farribeiro/patch-20