Make martial arts users immune to leg damage from bad kicks

Characters who have at least basic training in proper form for making
kicks are unlikely to fail to apply that training even if they decide to
kick a wall or heavy object. The kick won't necessarily accomplish
anything, but it will be properly executed. This removes the HP and
wounded leg damage in the "Ouch! That hurts!" kick failure case for all
characters with Basic martial arts (i.e. all monks and samurai) and
replaces it with an "ineffective" message. The kick still makes noise to
wake up monsters and still subjects the hero to Newton's 3rd Law.

Closes #151

doc/xnh-changelog-9.0.md

@@ -46,6 +46,8 @@ changes:
   paralyzed by lightning on the Plane of Air.
 - The bigroom variant which contains patches of light and darkness has a new
   variation with randomly generated "spotlights" of lit area.
+- Martial arts users with at least Basic skill (all monks and samurai) no longer
+  take damage or wound their legs when kicking inadvisable things.
 
 ### Interface changes
 

src/dokick.c

@@ -884,26 +884,37 @@ kick_ouch(coordxy x, coordxy y, const char *kickobjnam)
 {
     int dmg;
     char buf[BUFSZ];
+    /* this is explicitly NOT martial(), kicking boots do not
+     * protect from damage; this was initially "has Basic or higher in martial
+     * arts", but that happens to be equivalent to martial_bonus() anyway */
+    boolean mart = martial_bonus();
 
-    pline("Ouch!  That hurts!");
+    if (mart)
+        Your("kick is ineffective.");
+    else
+        pline("Ouch!  That hurts!");
     exercise(A_DEX, FALSE);
     exercise(A_STR, FALSE);
     wake_nearby();
     if (isok(x, y)) {
         if (Blind)
             feel_location(x, y); /* we know we hit it */
         if (is_drawbridge_wall(x, y) >= 0) {
-            pline_The("drawbridge is unaffected.");
+            if (!mart)
+                /* avoid similar message right after "ineffective" */
+                pline_The("drawbridge is unaffected.");
             /* update maploc to refer to the drawbridge */
             (void) find_drawbridge(&x, &y);
             gm.maploc = &levl[x][y];
         }
         wake_nearto(x, y, 5 * 5);
     }
-    if (!rn2(3))
-        set_wounded_legs(RIGHT_SIDE, 5 + rnd(5));
-    dmg = rnd(ACURR(A_CON) > 15 ? 3 : 5);
-    losehp(Maybe_Half_Phys(dmg), kickstr(buf, kickobjnam), KILLED_BY);
+    if (!mart) {
+        if (!rn2(3))
+            set_wounded_legs(RIGHT_SIDE, 5 + rnd(5));
+        dmg = rnd(ACURR(A_CON) > 15 ? 3 : 5);
+        losehp(Maybe_Half_Phys(dmg), kickstr(buf, kickobjnam), KILLED_BY);
+    }
     if (Is_airlevel(&u.uz) || Levitation)
         hurtle(-u.dx, -u.dy, rn1(2, 4), TRUE); /* assume it's heavy */
 }