Support unpinned ibts

See merge request allzp/zipr!12

Resolve "probNog has non-determinism and doesn't always work"

Closes #11

See merge request allzp/zipr!13

Make sure that Zipr does not produce segments with RWX permissions.

Closes #8

See merge request allzp/zipr!11

Use copy_if and max_element rather than for loops.

Fixes #8. This will match the gap-filling scoop's perms
with those of the adjacent scoop. Then, for any
gap-filling scoops that are not executable, fill their
contents with f4s.