Level temperature affects monster generation

Hot levels generate more fire-resistant monsters, cold
levels cold-resistant ones.

doc/fixes3-7-0.txt

@@ -1332,6 +1332,7 @@ demons cannot be frightened by showing them their reflection
 HP regeneration formula has changed, primarily to be less fast in the endgame
 riding negates stealth unless the steed is flying
 previous hero rising as undead in bones retains intrinsics
+level temperature affects monster generation
 
 
 Fixes to 3.7.0-x General Problems Exposed Via git Repository

src/makemon.c

@@ -16,6 +16,7 @@
 
 static boolean uncommon(int);
 static int align_shift(struct permonst *);
+static int temperature_shift(struct permonst *);
 static boolean mk_gen_ok(int, unsigned, unsigned);
 static boolean wrong_elem_type(struct permonst *);
 static void m_initgrp(struct monst *, coordxy, coordxy, int, mmflags_nht);
@@ -1606,6 +1607,17 @@ align_shift(register struct permonst *ptr)
     return alshift;
 }
 
+/* return larger value if monster prefers the level temperature */
+static int
+temperature_shift(struct permonst *ptr)
+{
+    if (gl.level.flags.temperature
+        && pm_resistance(ptr, (gl.level.flags.temperature > 0)
+                         ? MR_FIRE : MR_COLD))
+        return 3;
+    return 0;
+}
+
 /* select a random monster type */
 struct permonst *
 rndmonst(void)
@@ -1663,6 +1675,7 @@ rndmonst_adj(int minadj, int maxadj)
          * potentially steal its spot.
          */
         weight = (int) (ptr->geno & G_FREQ) + align_shift(ptr);
+        weight += temperature_shift(ptr);
         if (weight < 0 || weight > 127) {
             impossible("bad weight in rndmonst for mndx %d", mndx);
             weight = 0;