track eight more achievements

Record reaching experience level 3, 6, 10, 14, 18, 22, 26, and 30,
the levels where the character gets a new rank title, and report
those as achievements at end of game.  These achievements persist
even if enough levels to lose a rank are lost, and if lost ranks
are regained the original achievement is the one that gets tracked
and disclosed.

src/topten.c

@@ -474,13 +474,16 @@ boolean condition;
 static char *
 encode_extended_achievements()
 {
-    static char buf[N_ACH*40];
+    static char buf[N_ACH * 40];
+    char rnkbuf[40];
     const char *achievement = NULL;
-    int i;
+    int i, achidx, absidx;
 
     buf[0] = '\0';
     for (i = 0; u.uachieved[i]; i++) {
-        switch (u.uachieved[i]) {
+        achidx = u.uachieved[i];
+        absidx = abs(achidx);
+        switch (absidx) {
         case ACH_UWIN:
             achievement = "ascended";
             break;
@@ -517,7 +520,6 @@ encode_extended_achievements()
         case ACH_SOKO_PRIZE:
             achievement = "obtained_the_sokoban_prize";
             break;
-
         case ACH_ORCL:
             achievement = "consulted_the_oracle";
             break;
@@ -542,6 +544,15 @@ encode_extended_achievements()
         case ACH_BGRM:
             achievement = "entered_bigroom";
             break;
+        /* rank 0 is the starting condition, not an achievement; 8 is Xp 30 */
+        case ACH_RNK1: case ACH_RNK2: case ACH_RNK3: case ACH_RNK4:
+        case ACH_RNK5: case ACH_RNK6: case ACH_RNK7: case ACH_RNK8:
+            Sprintf(rnkbuf, "attained_the_rank_of_%s",
+                    rank_of(rank_to_xlev(absidx - (ACH_RNK1 - 1)),
+                            Role_switch, (achidx < 0) ? TRUE : FALSE));
+            strNsubst(rnkbuf, " ", "_", 0); /* replace every ' ' with '_' */
+            achievement = lcase(rnkbuf);
+            break;
         default:
             continue;
         }