Use macro for spell pw cost per spell level

include/spell.h

@@ -25,4 +25,7 @@ struct spell {
 #define spellid(spell) g.spl_book[spell].sp_id
 #define spellknow(spell) g.spl_book[spell].sp_know
 
+/* how much Pw a spell of level lvl costs to cast? */
+#define SPELL_LEV_PW(lvl) ((lvl) * 5)
+
 #endif /* SPELL_H */

src/spell.c

@@ -924,7 +924,7 @@ spelleffects(int spell_otyp, boolean atme)
      *  Note: dotele() also calculates energy use and checks nutrition
      *  and strength requirements; if any of these change, update it too.
      */
-    energy = (spellev(spell) * 5); /* 5 <= energy <= 35 */
+    energy = SPELL_LEV_PW(spellev(spell)); /* 5 <= energy <= 35 */
 
     /*
      * Spell casting no longer affects knowledge of the spell. A

src/u_init.c

@@ -932,10 +932,10 @@ u_init(void)
         break;
     }
 
-    /* If we have at least one spell, force starting Pw to be 5,
+    /* If we have at least one spell, force starting Pw to be enough,
        so hero can cast the level 1 spell they should have */
-    if (num_spells() && (u.uenmax < 5))
+    if (num_spells() && (u.uenmax < SPELL_LEV_PW(1)))
-        u.uen = u.uenmax = u.uenpeak = u.ueninc[u.ulevel] = 5;
+        u.uen = u.uenmax = u.uenpeak = u.ueninc[u.ulevel] = SPELL_LEV_PW(1);
 
     return;
 }