tracking peak maximum HP and energy

Keep track of the highest value that u.uhpmax and u.uenmax have
attained, in new u.uhppeak and u.uenpeak.  They aren't used for
anything yet.  u.mhmax (max HP while polymorphed) isn't interesting
enough to track.

Not save and bones compatible so increments EDITLEVEL.

src/exper.c

@@ -289,11 +289,15 @@ pluslvl(boolean incr) /* true iff via incremental experience growth */
     }
     hpinc = newhp();
     u.uhpmax += hpinc;
+    if (u.uhpmax > u.uhppeak)
+        u.uhppeak = u.uhpmax;
     u.uhp += hpinc;
 
     /* increase spell power/energy points */
     eninc = newpw();
     u.uenmax += eninc;
+    if (u.uenmax > u.uenpeak)
+        u.uenpeak = u.uenmax;
     u.uen += eninc;
 
     /* increase level (unless already maxxed) */