fast and structured logging package for Go

 This is a fork of the exellent Apex Log (https://github.com/apex/log)
 library.
 .
 Main changes:
 .
  * Trim unneeded dependencies.
  * Make Fields into a slice to preserve log order.
  * Split the old Interface in two and remove all but one Log method (see
    below).
  * This allows for lazy creation of messages in Log(fmt.Stringer) and
    ignoring fields added in LevelLoggers with levels below the Loggers.
  * The pointer passed to HandleLog is not safe to use outside of the
    current log chain, and needs to be cloned with Clone first if that's
    needed.
 .
 This is probably the very fastest structured log library when logging is
 disabled.