OnlyWorlds Unity SDK 0.6.0

A world folder that Atlas wrote now opens whole: its pins' and markers' links, and the older spatial/ layout.
A minor release because it adds public API (below).

Fixed

• A world folder's pins and markers keep their links when Atlas spelled them map_id and zone_id. The spec
  says a reader accepts both spellings, and Atlas writes the _id forms. OWFolderLoader.LoadInto gave the cache the
  body as written, so a pin from an Atlas folder had no Map and a marker no Map or Zone. The cache now gets
  OWFolderReader.WithSchemaLinkNames(body): the schema's name, in the old one's place, when the schema's name is not
  already there. The read result's bodies and the files on disk are unchanged.
• One id, one file (folder spec v0.3.8 §4). Where an older Atlas folder holds one id in both elements/ and
  spatial/, OWFolderReader.Read serves elements/ and logs the spatial/ copy in Skipped (it used to be loaded
  last, so the older copy won in the cache). OWFolderWriter.WriteElement writes a map, pin, zone or marker that
  lives under spatial/<type>/ there, in its own file, so an edit never leaves a second copy; a new element goes to
  elements/. OWFolderExport stamps format_version "0.3.8", as the Python package does since its 0.5.0.

Added

• OWFolderReader.WithSchemaLinkNames(body): a body's links under the schema's names (map_id as map, zone_id
  as zone), a copy when anything differs; what the cache is given.
• OWFolderReadResult.TimeCurrent: time_current, else the wire's time_range_current (both accepted, as the
  Python package reads them). OWFolderReadResult.ServerWorldId: a linked folder's api.world_id, else its id.
  WorldId stays the folder's own id, which keys the cache.
• The reader's notes name the folder spec it follows: v0.3.8's reading rules (they said v0.3.5).