0.5.0

• Added rawMsg property to LogEvents to store message without
  string interpolation (i.e. the original string that still contains
  the placeholders from either sprintf() or glue()) (#60)

• Updated AppenderConsole to accept a connection argument. If called from a
  {knitr} rendering process, log messages are now output to stderr instead
  of stdout by default. This avoids polluting markdown documents (#62, thx @gadenbuie).

• Replace NULL values and empty characters in logging by the string "<NULL>".
  Before, NULL values would have resulted in empty log messages. (#51)

• Support transformers for LoggerGlue (see ?glue::glue) (#51)

• Add excluded_fields to Layout for excluding fields from logging.

• Add transform_event and transform_event_names to LayoutJson to make
  it more flexible. Exclude rawMsg by default for backwards compatibility.