Follows hyperfile 0.11.0 and its new StreamSegment format: collect, prune,
report and compact work on a container in that format.

A data part of a StreamSegment container is a compaction candidate even while it
holds a live leaf of the block map, since that layout keeps every leaf in the
object with its data and relocating the data rewrites the leaf. Part 0, and
every other format, are as before.

A format this build cannot read is now refused instead of read as MicroGroup.
A 0.10.5 cleaner reading a StreamSegment container that way reports every
object unreferenced, the newest checkpoint included. The walk also checks that
the summary it read is the checkpoint asked for and that the listing names it.

Requires hyperfile 0.11.0.