1.6.0

• Docker main script rewritten to Python and changed to use per project workflow
  • see https://github.com/oracle/opengrok/wiki/Per-project-management-and-workflow
• OpenGrok now requires Tomcat 10
  • or container that supports Servlet API 5
• Python tools now support custom HTTP headers everywhere
  • this is handy when running indexer in separate machine/VM so that API token
    can be used
• history cache item creation times now reported with FINER log level