Early abort for forEach, peek multiple

Adds the capability to peek at multiple entries at the head of the
queue. I didn't have to change QueueFile, as its forEach already can
avoid reading bytes, but this optimization to abort early saves some
object creation.

Not a breaking API change.
Spacing was off.  What's the standard for inline array init like this?  The rest of the file does not have spaces around the first, last elements.