Issue description
I have a Problem my Tradeship won't Unload her freight and don't Load stored cargo.
I know i haven't enough Unity to send the Ship, but should the ship at least load the existing cargo?

Reproduction steps
I signed a contract.
I don't want to cancel the contract; there's not enough Unity to sign it again, but removing the assignment isn't working.
Game version and build number
0.8.2C
Operating system
Windows