Fix maxNoDamageTicks being cut in half

For no apparent reason, noDamageTicks was counting down from maxNoDamageTicks to maxNoDamageTicks/2. Both of these values can be set through the Bukkit API, but there is no correction for this strange offset. As a result, the value passed to setMaxNoDamageTicks would effectively be cut in half, and the value passed to setNoDamageTicks would be reduced by maxNoDamageTicks/2.