land units and nukes for selection type NS_LIST. Thus, unowned items
explicitly selected by item number are skipped, while the same items
selected implicitely by group, area or whatever are not. This makes
no sense. Some callers break the nstr_item abstraction to prevent the
skipping, so they get all items regardless of how they were selected.
All other callers filter out unowned items. This skipping misfeature
dates back to the very oldest known versions of Empire. Remove it.
Also remove skipping prevention hacks from callers.
(tend_nxtitem): Now identical to nxtitem(), except it lacks some extra
normalization of item coordinates, which should have no effect.
Replace by nxtitem().
defines, import these defines into plague.h, drop var.h and include
plague.h where appropriate.
Remove some 'register' keywords at the same time.
No functional changes.
To save space, the ancients invented `variables': a collection of
key-value pairs, missing means zero value, space for `enough' keys.
This complicates the code, as assigning to a `variable' can fail for
lack of space. Over time, `enough' increased, and for quite some time
now `variables' have been *wasting* space. This changeset replaces
them, except in struct mchrstr, struct lchrstr and struct pchrstr,
where they are read-only, and will be replaced later. It is only a
first step; further cleanup is required. To simplify and minimize
this necessarily huge changeset, the new item[] arrays have an unused
slot 0, and the old variable types V_CIVIL, ... are still defined, but
must have the same values as the item types I_CIVIL, ...
