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/fountain.c

@@ -524,7 +524,8 @@ drinksink()
 		case 2: You("take a sip of scalding hot water.");
 			if (Fire_resistance)
 				pline("It seems quite tasty.");
-			else losehp(rnd(6), "sipping boiling water", KILLED_BY);
+			else losehp(Maybe_Half_Phys(rnd(6)),
+					"sipping boiling water", KILLED_BY);
 			break;
 		case 3: if (mvitals[PM_SEWER_RAT].mvflags & G_GONE)
 				pline_The("sink seems quite dirty.");