item types was removed some time ago. Simplify.
(VT_ITEM, VT_TYPE, V_MAX): Unused, remove.
(show_sect_capab): Properly use ichr[] member i_mnem to print item
characters.
Store only up to MAXPRCON constituents, not MAXCHRNV; code doesn't
fully support more than three anyway. Remove member p_nv, use item
type I_NONE for unused slots. Rename members p_vtype, p_vamt to
p_ctype, p_camt to avoid confusion with variable-style storage.
(pchr): Initializers adapted.
(nullify_objects, materials_cost, materials_charge, prod,
show_sect_capab, grind): Adapt, simplify where possible, protect
against bad item types in pchr[].
(MAXCHRNV): Unused, remove.
(upd_ship): Oil and food production used special rules that didn't
match ordinary production and didn't make much sense. Made them
follow ordinary production rules. This puts uw and mil to work, and
makes ship tech and efficiency relevant to production. Closes#917461
and #955072.
This can't happen currently, because produce() never gets called with
work>999.
(produce): Fix rounding of consumed materials on production backlog.
Broken by the previous revision.
arrays instead of copies made by getvec(). This is safe, because the
old code made single copies and always flushed them back into the unit
structures. Else make copies by hand, not with getvec.
(starv_sects): Replace getvec() by direct, read-only item access.
(upd_buildeff, enlist, materials_charge, materials_cost, produce,
grow_people, growfood, trunc_people, do_feed, feed_people): Change
argument type to match uncopied item arrays.
(growfood): Obey ITEM_MAX.
