Half_physical_damage 06

- [fixed in trunk] Alchemical explosion
- [fixed in trunk] Artifacts' blasting
- [fixed in trunk] Boiling/freezing potions
- [fixed in trunk] Chest/door/tin traps
- [fixed in trunk] Falling rocks/boulders (trap, digging, scroll of earth)
- [fixed in trunk] Mixing water and acid
- [fixed in trunk] Thrown potion (acid)

This is my last patch on this today.

src/artifact.c

@@ -529,7 +529,7 @@ touch_artifact(obj,mon)
 	You("are blasted by %s power!", s_suffix(the(xname(obj))));
 	dmg = d((Antimagic ? 2 : 4), (self_willed ? 10 : 4));
 	Sprintf(buf, "touching %s", oart->name);
-	losehp(dmg, buf, KILLED_BY);
+	losehp(dmg, buf, KILLED_BY); /* magic damage, not physical */
 	exercise(A_WIS, FALSE);
     }