motion: hold, eat and drink standing and walking, not only seated (a camp drinks at a barrel) #842

motion.hold, eat and drink (#839) work only while seated (ACTION_SIT): hold returns false standing, and carry_held runs only in the seated branch of step_way. A camp asks for more: Siltreach's settlers drink standing at a water barrel. They also carry a bowl or a cup to a seat, which is #825's "carry".

What's needed, measured the way test_eat measures sitting:

• Hold standing. A POWERED figure holds a thing in one hand or two while it stands. Its arms carry the thing at the chest or at the side, with the palms on the grips. That's the forearm body's far end, under 3 cm off.
• Drink and eat standing. The same raise, stay and lower as sitting (BITE_RAISE, BITE_STAY, BITE_LOWER). The rest of the body keeps its balance, with no step taken and no foot sliding.
• Walk while holding. go_to while holding keeps the palms on the grips and the thing level within CUP_TILT. A full cup spills nothing.
• Sit and stand holding. sit and stand_up keep a held thing in the hands. Today stand_up puts it down first.

Each with a test that fails without it, like tests/test_eat.ae.