CHANGE: Remove gear values for boats and ships
REMOVE: Double boat horse (in reality, canal boats were always hauled by single horses, except for fly-boats, which already have their own type of horses)
CHANGE: Increase the maximum speed of unpowered canal boats to take advantage of the higher speed of the towpath tractor.
FIX: Fly boat horses could not be used with the packet barge.
CHANGE: Increase the space between boat horses and the towpath tractor and the boats being towed
FIX: Increase the speed of the packet barge
CHANGE: Increase the capacity of the narrow fly-boat