(empfile, SYMTAB): Reorder so that symbol tables are together. Sort

them alphabetically.  Factor out commonalities into new SYMTAB().  No
functional changes.

include/file.h

@@ -122,31 +122,32 @@ enum {
     EF_LAND_CHR,
     EF_NUKE_CHR,
     EF_NEWS_CHR,
-    EF_TREATY_FLAGS,
     EF_ITEM,
     EF_INFRASTRUCTURE,
     EF_PRODUCT,
     EF_TABLE,
-    EF_SHIP_CHR_FLAGS,
-    EF_PLANE_CHR_FLAGS,
-    EF_LAND_CHR_FLAGS,
-    EF_NUKE_CHR_FLAGS,
     EF_META,
-    EF_META_TYPE,
+    /* Symbol tables */
+    EF_AGREEMENT_STATUS,
+    EF_LAND_CHR_FLAGS,
+    EF_LEVEL,
     EF_META_FLAGS,
+    EF_META_TYPE,
     EF_MISSIONS,
-    EF_PLANE_FLAGS,
-    EF_RETREAT_FLAGS,
     EF_NATION_FLAGS,
     EF_NATION_RELATIONS,
-    EF_LEVEL,
-    EF_AGREEMENT_STATUS,
-    EF_PLAGUE_STAGES,
-    EF_PACKING,
-    EF_RESOURCES,
     EF_NATION_STATUS,
-    EF_SECTOR_NAVIGATION,
+    EF_NUKE_CHR_FLAGS,
+    EF_PACKING,
     EF_PAGE_HEADINGS,
+    EF_PLAGUE_STAGES,
+    EF_PLANE_CHR_FLAGS,
+    EF_PLANE_FLAGS,
+    EF_RESOURCES,
+    EF_RETREAT_FLAGS,
+    EF_SECTOR_NAVIGATION,
+    EF_SHIP_CHR_FLAGS,
+    EF_TREATY_FLAGS,
     /* Views */
     EF_COUNTRY,
     /* Number of types: */