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/mthrowu.c

@@ -73,8 +73,7 @@ const char *name;	/* if null, then format `obj' */
 			pline("It doesn't seem to hurt you.");
 		else {
 			if (is_acid) pline("It burns!");
-			if (Half_physical_damage) dam = (dam+1) / 2;
-			losehp(dam, knm, kprefix);
+			losehp(Maybe_Half_Phys(dam), knm, kprefix);
 			exercise(A_STR, FALSE);
 		}
 		return(1);