v0.4.0

Changelog

• Add @timestamp diff highlighting:
  the part of the timestamp that has changed from the preceding record is
  underlined (in the default color scheme). This highlighting can be turned
  off with the timestampShowDiff: false config var.
  (#20)

• Add ecsLenient: false config option to allow rendering of lines that are
  likely ECS-compatible, but do not have all three required ecs-logging fields:
  @timestamp, ecs.version, log.level. Only one of those three is required
  to be rendered.

  This intentially doesn't have a command-line option for now. Currently it is
  considered a crutch for ES 8.x and Kibana 8.x logs that, at time of writing,
  are missing one or two of the above fields. If that is long-standing,
  ecsLenient: true might eventually become the default.