Add level flag for plane of fire fumaroles

Also reduce the size of the gas clouds.

Breaks saves and bones.

src/allmain.c

@@ -333,7 +333,7 @@ moveloop_core(void)
                 /* vision will be updated as bubbles move */
                 if (Is_waterlevel(&u.uz) || Is_airlevel(&u.uz))
                     movebubbles();
-                else if (Is_firelevel(&u.uz))
+                else if (gl.level.flags.fumaroles)
                     fumaroles();
 
                 /* when immobile, count is in turns */

src/do.c

@@ -1730,7 +1730,7 @@ goto_level(
     /* initial movement of bubbles just before vision_recalc */
     if (Is_waterlevel(&u.uz) || Is_airlevel(&u.uz))
         movebubbles();
-    else if (Is_firelevel(&u.uz))
+    else if (gl.level.flags.fumaroles)
         fumaroles();
 
     /* Reset the screen. */

src/mkmaze.c

@@ -1390,15 +1390,25 @@ mkportal(coordxy x, coordxy y, xint16 todnum, xint16 todlevel)
 void
 fumaroles(void)
 {
-    xint16 n;
+    xint16 n, nmax = rn2(3);
+    int sizemin = 5;
     boolean snd = FALSE, loud = FALSE;
 
-    for (n = rn2(3) + 2; n; n--) {
+    if (Is_firelevel(&u.uz)) {
+        nmax++;
+        sizemin += 5;
+    }
+    if (gl.level.flags.temperature > 0) {
+        nmax++;
+        sizemin += 5;
+    }
+
+    for (n = nmax; n; n--) {
         coordxy x = rn1(COLNO - 4, 3);
         coordxy y = rn1(ROWNO - 4, 3);
 
         if (levl[x][y].typ == LAVAPOOL) {
-            NhRegion *r = create_gas_cloud(x, y, rn1(30, 20), rn1(10, 5));
+            NhRegion *r = create_gas_cloud(x, y, rn1(10, sizemin), rn1(10, 5));
 
             clear_heros_fault(r);
             snd = TRUE;

src/sp_lev.c

@@ -3747,6 +3747,8 @@ lspo_level_flags(lua_State *L)
             gl.level.flags.deathdrops = 0;
         else if (!strcmpi(s, "noautosearch"))
             gl.level.flags.noautosearch = 1;
+        else if (!strcmpi(s, "fumaroles"))
+            gl.level.flags.fumaroles = 1;
         else {
             char buf[BUFSZ];
             Sprintf(buf, "Unknown level flag %s", s);