(dchr_ca, packing, empfile): Add packing symbol table.

(sect_ca, ship_ca, land_ca, plague_stages, empfile):
Add plague stages symbol table.

(treaty_ca, loan_ca, agreement_statuses, empfile):
Add agreement status symbol table.
Combine treatystatuses (TS_FREE, TS_SIGNED and TS_PENDING)
and loan statuses (LS_FREE, LS_SIGNED and LS_PENDING)
into a single agreement status.

(pchr_ca, level, empfile): Add packing symbol table.

include/treaty.h

@@ -48,9 +48,9 @@ struct trtstr {
     time_t trt_exp;		/* expiration date */
 };
 
-#define TS_FREE		0
-#define TS_PROPOSED	1
-#define TS_SIGNED	2
+#define TS_FREE		AGREE_FREE
+#define TS_PROPOSED	AGREE_PROPOSED
+#define TS_SIGNED	AGREE_SIGNED
 
 	/* treaty clauses */
 #define	LNDATT	bit(0)		/* no attacks on land units */