Calculate the Initial Delay of Replenishment Early

[jpwilliams]

Instead of having sums once the server starts, save the value as the initial delay rather than the harder-to-understand timer value.

For example, if an item replenishes every 24,000 ticks and the task has run for 18,000 ticks, instead of

apple:
  replenishtimer: 18000

We could have

apple:
  nextReplenishIn: 6000

Much easier to understand and should make code a lot cleaner as well.