RFE: included all blown off limbs in salvage

When a limb is blown off in a scenario, it is only claimable as salvage if the unit it was attached to was also salvaged. If the player retains control of the field at the end of a scenario and an enemy unit retreats while leaving a blown off limb behind, the limb is not available for salvage.

Please include blown off limbs in the battlefield salvage process even if the source unit has retreated. Ideally this would also include limbs picked up and carried off the field regardless of whether the field is held or not.

This can be presented during scenario resolution as an extension to the normal salvage page below the unit salvage list, showing them like this:

Right arm (Phoenix Hawk PXH-1)

... with the usual check box for salvage. There doesn't need to be a checkbox for "Retreated" but it would be nice to have the "Ransom" option. The cost of limb salvage should also be considered for overall salvage percentage.

Storage is currently by individual parts only so I'm not certain where things should proceed after this. Ideally there would be changes to enable storing entire limbs as they are, but that might be handled better as a separate change. It may be necessary for a first-pass effort to automatically break the limb down to it's constituent parts in a way so that full limb storage can be implemented later if called for.