Replaced fuel_consumption stat with fuel_consumption characteristic.

fuel_consumption is a flat variable, but ship stats are clearly
meant to be midifiers. This resulted in the game telling the player
that fuel_consumption was a modifier. It's now a (mandatory)
characteristic of the ship instead. This also avoids the problem of
the arbitrary 100 fuel default consumption.

Ships haven't been updated yet. That will be done next commit.

I also removed a bunch of ship info from the shipyard that is
outdated (i.e. characteristics that are no longer used, and that are
now determined by outfits and ship stats).
Updated all ships to use fuel_consumption, with one exception.

I didn't update the Reverance because that ship needs other updates
to it as well. It seems to have been left behind when the core
systems were added.
Updated Sirius Reverence.