Merge pull request #484 from xytovl/dev

Fix some exceptions in advanced window transfer
Quick fix for handling engine parts with multiple gimbal modules.
Merge pull request #490 from ozraven/dev

Quick fix for handling engine parts with multiple gimbal modules.
Change how Velocity is calculated as mentioned in #478
Revert "Change how Velocity is calculated as mentioned in #478"

This reverts commit 1d5fb05db76a1c8e87c152b2e29c9504b8338277.
Fix landing site selection on other bodies than Kerbin
Do not throw exceptions in advanced transfer precondition check
Allow advanced transfer with no safe time margin