6.6.3

• New Definition List Colon (MARKER_DEFLIST_COLON) token (fletcher/f6f4869) and Object Replacement (OBJECT_REPLACEMENT_CHARACTER) token (fletcher/d2d14d0)
• Update re2c generated lexer files (fletcher/ba334a0)
• Added DISABLE_OBJECT_POOL as a compiler flag to disable token pools (fletcher/99b9bf4). The previous MMD_SHOULD_ENABLE_TOKEN_POOL still works too and the token pool is still disabled by default, as with previous releases.
  However, using the packages now requires Swift 5.0 (up from 4.2), to be able to set cSettings in the Package.swift package manifest.