Carrying capacity
=================

Men and items are rated for how much they weigh, and how much they can
carry, walking, riding or flying.

                        weight   walking    riding   flying
                        ------   -------    ------   ------
        man               100      100        -         -
        riding horse      300      150       150        -
        wild horse        300      self      self       -
        warmount          300      150       150        -
        knight            400      100       100        -
        elite guard       400      100       100        -
        ox               1000     1500       self       -
        winged horse      300      150       150       150

"man" includes all of the varieties of men, including peasants, sailors,
workers, etc. as well as nobles.  A knight includes both the man and the
horse, hence the 400 weight.

In order to ride, the total riding capacity must cover the weights
of all the units that may not ride themselves.

Examples:

        man + riding horse:     ride capacity is 150 - 100 = 50
                                walk capacity is 250

        man + riding horse +
        wild horse:             ride capacity is 150 - 100 = 50
                                walk capacity is 250

                                The wild horse can walk or ride on
                                its own, but will not carry anything.

        man + riding horse +
        ox:                     ride capacity is 150 - 100 = 50
                                walk capacity is 1750

                                The ox may be driven alongside the
                                horse, but will not carry anything
                                when moving so quickly.

A stack will ride if there is enough riding capacity to carry all
of the non-riders.  Otherwise, the stack will walk.

In order to fly, the total flying capacity for the stack must cover
the weights of all units that can not fly themselves.

Stacks which are overloaded beyond their walking capacity will travel
slower than normal.  A stack loaded at 150% of its walking capacity
will take 50% longer to traverse a route.  Stacks overloaded to over
200% of walking capacity may not travel at all.

Weights and capacities are always considered for the stack as a whole.
One unit may have all the men, and another unit may have all the horses.
If they are stacked together, the distribution of items across units
is irrelevant.