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.
capacities to straight arrays. Users now subscript the array instead
of calling vl_find() or walking the variable data structure.
(mchr, lchr): Initializers adapted.
(vl_find): No longer used. Remove file.
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, ...
