Exercise load, unload, lload, lunload, tend, and ltend.
Notable coverage gaps:
* Effect on land unit fortification
* Effect on mission and retreat orders
* Ships, land units and planes on sale (option MARKET 1)
* Transmission of plague (option NO_PLAGUE 0)
* Land units loading and unloading civilians (need a custom land unit
type capable of carrying civilians)
* load refusing to load x-light planes (need a custom ship type that
can carry helo but not x-light)
* load and lload refusing to load land units carrying land units, and
lload refusing to load land units onto land units that are being
carried (need a custom non-heavy land unit type that can carry land
units)
* tend refusing to tend non-light land units to non-supply ships, or
to supply ships without room (need custom a non-light assault land
unit type)
This test exposes bugs. They're marked "BUG:" in the test input.
There are also oddities marked "odd:", and usability issues marked
"usability:".
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
