- Implement code line/func/etc. (only for debug?):
https://stackoverflow.com/a/24809646
https://golang.org/pkg/runtime/#Caller
-- log.LlongFile and log.Lshortfile flags don't currently work properly for StdLogger/FileLogger; they refer to the file in logging package rather than the caller.
- Suport remote loggers? (eventlog, syslog, systemd)
- JSON logger? YAML logger? XML logger?
- DOCS.
-- Done, but flesh out.