Suggested features and improvements

• allow multiple write policies to either share the same or use several different formatting policies (hs)
• make the library mutli-thread safe so that multpiple threads can log at the same time (hs)
• there should be more/better example code to explain how to use this (ck)
• implement some alternative to TEMPLOG_LOG that sets reasonable defaults for severity and audience and implicitly uses the global logger (ck)
• add a formatting policy that emits a timestamp (ow)
• find a way to specify how often to see a specific log message at most (cu)
• create an alternative to TEMPLOG_LOG that allows using a different severity/audence/logger depending on a specifc condition in the user's code (cu)
• let a specific log message be reported only every N seconds, disregarding all other instances (cu)