v4.8.4

Changes since v4.8.3:

Changes to internals:

• Simplify configuration by introducing a defaults file
• Allow any configuration to be overridden in the user-specific config file
  (though please note that local overrides can make updates more complex)
• Remove old release note format from manifest.json

And some minor bug fixes:

• Fix type of http_build_query() argument in oauth-listener/index.php
• Fix notice when additional sessions are active, 'Undefined array key "session_id"'

v4.8.3...v4.8.4

SHA-256 checksum for platform.phar:
5cd9ff5919410c30b56b1ffdb0d15980635c45a9d3a278efb85d6a1f40fe29e0