Bugfixes:

• #828: Fix missing newline in IncreaseLevel error messages.
• #835: Fix panic in JSON encoder when encoding times or durations
  without specifying a time or duration encoder.
• #843: Honor CallerSkip when taking stack traces.
• #862: Fix the default file permissions to use 0666 and rely on the umask instead.
• #854: Encode <nil> for nil Stringer instead of a panic error log.

Enhancements:

• #629: Added zapcore.TimeEncoderOfLayout to easily create time encoders
  for custom layouts.
• #697: Added support for a configurable delimiter in the console encoder.
• #852: Optimize console encoder by pooling the underlying JSON encoder.
• #844: Add ability to include the calling function as part of logs.
• #843: Add StackSkip for including truncated stacks as a field.
• #861: Add options to customize Fatal behaviour for better testability.

Thanks to @SteelPhase, @tmshn, @lixingwang, @wyxloading, @moul, @segevfiner, @andy-retailnext and @jcorbin for their contributions to this release.