Tone down scare monster by excluding humans and uniques

Scroll of scare monster completely shut down most of the actual
challenging monsters, such as uniques. Tone it down, so you can
use it to ignore the smaller threats while dealing with uniques,
or get most of the effect in the early game when you're usually
dealing with normal monsters.

src/monmove.c

@@ -135,10 +135,13 @@ int x, y;
 struct monst *mtmp;
 {
     /* creatures who are directly resistant to magical scaring:
+     * humans aren't monsters
+     * uniques have ascended their base monster instincts
      * Rodney, lawful minions, Angels, the Riders, shopkeepers
      * inside their own shop, priests inside their own temple */
     if (mtmp->iswiz || is_lminion(mtmp) || mtmp->data == &mons[PM_ANGEL]
         || is_rider(mtmp->data)
+        || mtmp->data->mlet == S_HUMAN || unique_corpstat(mtmp->data)
         || (mtmp->isshk && inhishop(mtmp))
         || (mtmp->ispriest && inhistemple(mtmp)))
         return FALSE;