Fix refresh creating an infinite timeout loop

[Thomas101]

If the date is more than a week away, then the refresh period would be set to Infinity. This gets passed to a setTimeout, which fires immediately causing a refresh loop, which in my instance resulted in 100% cpu usage.

It could also be the cause of #160

The code already does a true-y check on period before issuing the setTimeout, this patch also explicitly checks for Infinity to ensure that the timeout doesn't fire

Infinite timeouts are a bit of a js quirk that really don't behave as expected - https://github.com/denysdovhan/wtfjs#an-infinite-timeout

[nmn]

If Infinity is causing this problem, let’s replace Infinity with a very large number instead?

[Thomas101]

Yeah that sounds reasonable. I don't know if you're thinking very large as in Number.MAX_SAFE_INTEGER or just far enough in the future.

I set it to a week for now, unless it's a long-running app then it should never fire and if it is running for a long period a week makes sense from the unboundPeriod tree and performance point of view. Happy to update the PR if you think Number.MAX_SAFE_INTEGER or something else would be more suitable.

Also changed the maxPeriod default option. This was set to Infinity so without the guard invokes the same bug.

[nmn]

Would you mind bumping the minor version number as well?