minor, make FOREACH_RBN return ftnd_t nodes, and provide FOREACH_RBN_FACT
minor, get a private piece of fof for the ftmap
minor, PEBKAC, actually sort both the ftm facts as well as their offsets
Merge branch 'backend/dsk'

* backend/dsk:
  minor, PEBKAC, actually sort both the ftm facts as well as their offsets
  minor, get a private piece of fof for the ftmap
  minor, make FOREACH_RBN return ftnd_t nodes, and provide FOREACH_RBN_FACT
minor, eradicate echs_instant_t param from ftmap_put_last()

Its value is easily determined.
minor, provide binary search on page_s objects and bring back _get_as_of_now()
test, optionally find facts in rolf-pump-dsk(1) given as fact numbers in the command line
test, chore, force bitte_get() into using as_of_then() timeslice query
minor, make return values to page_ftm_get() const
minor, provide working _get_as_of_then()
minor, bound the search for *_first_after on the way backwards through the pages
Merge branch 'backend/dsk'

* backend/dsk:
  minor, bound the search for *_first_after on the way backwards through the pages
  minor, provide working _get_as_of_then()
  minor, make return values to page_ftm_get() const
  test, chore, force bitte_get() into using as_of_then() timeslice query
  test, optionally find facts in rolf-pump-dsk(1) given as fact numbers in the command line
  minor, provide binary search on page_s objects and bring back _get_as_of_now()
  minor, eradicate echs_instant_t param from ftmap_put_last()
major, only allow ISO 8601 stamps sep'd by `T'
hygiene, don't inc+dec, just inc in the case where we want inc'ing
fix, PEBKAC, if hi in bsearch(3) is exclusive, make the comparison exclusive too
Merge branch 'core/instant'

* core/instant:
  fix, PEBKAC, if hi in bsearch(3) is exclusive, make the comparison exclusive too
  hygiene, don't inc+dec, just inc in the case where we want inc'ing
  major, only allow ISO 8601 stamps sep'd by `T'