Sectors need space for items, deliveries and distribution thresholds.

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, ...

src/lib/commands/set.c

@@ -109,8 +109,8 @@ set(void)
 		if (land.lnd_own == player->cnum)
 		    tot_mil += total_mil(&land);
 	    }
-	    if (tot_mil + (getvar(V_MILIT, (char *)&sect, EF_SECTOR)) * 10
-		< getvar(V_CIVIL, (char *)&sect, EF_SECTOR)) {
+	    if (tot_mil + sect.sct_item[I_MILIT] * 10
+		< sect.sct_item[I_CIVIL]) {
 		pr("Military control required to sell goods.\n");
 		return RET_FAIL;
 	    }