v2.6.8: VERSION: 2.6.8

• (ddr-defs) Replaced old top-down "inheritable" attribute with new
  bottom-up "inherits" attr.
• (ddr-defs) Moved repo_models.(entity,segment).TEMP_scrub_topicdata
  to DDR.vocab
• (ddr-cmdln) Changes to object diff functions to account for
  processing when objects are loaded.
• (ddr-cmdln) Switched to Elasticsearch "query_string" search parser,
  which enables boolean search, parentheses, and other
  useful things.
• (ddr-cmdln) Set default search operator to 'AND'.
• (ddr-cmdln) Added commandline "ddrindex search" command with all
  features of web UI search.
• (ddr-cmdln) Fixed bug that prevented access file generation for
  images larger than 768MB.
• (ddr-cmdln) Changed topics term path separator from ":" to "--".
• (ddr-cmdln) Replaced old argparse commands with new Click versions:
  ddrconfig, ddrinfo, ddrcheckbinaries, ddrcheckencodng,
  ddrtransform.
• (ddr-cmdln) All file I/O is now routed through DDR.fileio
  functions that offer UTF8 strict mode.
• (ddr-cmdln) Switched to new bottom-up inheritance model.
• (ddr-cmdln) New objects inherit inheritable fields from parent
  objects.
• (ddr-cmdln) Inheritable fields no longer have to have matching
  field names.
• (ddr-cmdln) requirements: pytest>=2.8.0,<4 (tox doesn't like
  pytest 4?)
• (ddr-local) search: Moved search code to ddr-cmdln
• (ddr-local) search: Redirect if fulltext is a valid DDR ID
• (ddr-local) Makefile: Removed openjdk-8-jre from .deb dependencies
• (ddr-local) Makefile: Correct paths for uncompressing static assets
• (ddr-local) conf,Makefile: Custom Imagemagick policy.xml to enable
  large file uploads
• (ddr-local) Makefile: Various changes to enable usage of
  git-worktree in development environment.
• (ddr-local) Object inheritance code moved to ddr-cmdln.