Add ability to customize level values

Fix Context.Stack() (rs#303)

Fix typo in diode.NewWriter argument name (rs#254)

stringer event method (rs#185)

Fix test on non linux platform

Fix trace again

Remove Trace from SyslogWriter interface

Expose the Err helper from the global logger

make TimeFormatUnixMicro var exportable (rs#189)

Fix a few typos / clarify. (rs#169)