Sacrificing artifacts. [Code is one giant workaround but should work good enough.] Updated changelog.

server/NetPacksServer.cpp

@@ -162,6 +162,8 @@ bool TradeOnMarketplace::applyGh( CGameHandler *gh )
 		return gh->buySecSkill(m, hero, r2);
 	case CREATURE_EXP:
 		return gh->sacrificeCreatures(m, hero, r1, val);
+	case ARTIFACT_EXP:
+		return gh->sacrificeArtifact(m, hero, r1);
 	default:
 		COMPLAIN_AND_RETURN("Unknown exchange mode!");
 	}