Build Mode with Safe Mode on should prevent changes that would automatically dump cargo

[Seamus Donohue]

Consider the case of a player making changes to a ship in Build Mode while that ship is carrying cargo.

Currently, if the player reduces the overall cargo capacity to below what is needed for the current cargo, then the excess cargo is automatically dumped into space and the player is prohibited from picking it up again for 2 minutes.  This happens whether Safe Mode is on or off.

I propose that if Safe Mode is on and the player attempts to reduce the cargohold capacity below what's needed for the current cargo, then the operation is stopped with the error message "Removing that much cargohold capacity would dump some cargo into space.  Transfer or sell some cargo before trying again."

[AvorionCraft]

Alternatively---cargo is held until buildmode is exited if the player is choosing to cut cargo down--and a message flashes (you are about to lose cargo!) before exiting.