(IPKG): New.

(ichr): Set IPKG packing bonus for all sectors to 1.
(move): Use it.  No functional change.
(deliver, dodistribute): Use it.  Inefficient sectors now get IPKG
instead of NPKG packing bonus, cutting civilian packing bonus from 10
to 1.

(dodistribute): Export uses the better of sector or distribution
center packing bonus.  Previously, it assumed that distribution center
WPKG packing is always best.  Which is currently true, but needlessly
breaks the abstraction.

include/item.h

@@ -35,6 +35,7 @@
 #define _ITEM_H_
 
 typedef enum {
+    IPKG,			/* "inefficient" packaging (eff<60) */
     NPKG,			/* no special packaging */
     WPKG,			/* "warehouse" packaging */
     UPKG,			/* "urban" packaging */