v0.11.1

Fixes:

• GET /ns/{ns}/rev/{at}/heads pages in time proportional to the page, not the
  namespace. Each page used to list every name and resolve every head at at, and only
  then page, so listing a namespace cost O(N²): about 14 s for 20 000 documents on SQLite
  and 14 minutes for 50 000 on Postgres. A page now takes its names from the (ns, name)
  index after the cursor, in byte order (on Postgres, a new name COLLATE "C" index),
  and resolves only those. Names with no head at at are skipped by fetching further
  chunks. Reported by an implementer.

Full Changelog: v0.11.0...v0.11.1