Adding Event.Type(...) method to log the type of an object

[w3aponx]

I found myself wanting to log the type of an object and was convinced there would be a method to do that already, but I didn't find one. Here's a case where one might want such a method:

	var value interface{}
	var result string
	switch v := value.(type) {
	case int:
		result = strconv.Itoa(v)
	case string:
		result = v
	default:
		log.Panic().Type("type", v).Msg("Unexpected value type")
	}
	log.Info().Msg(result)

Let me know if there's anything else that needs to change for this to get accepted.

[w3aponx]

@rs are you waiting for any more changes here? Just wanted to make sure because AFAIK the requested changes were implemented a while back and I'm not sure how I can convey that any better than by requesting another review. If it's just that you've been busy with other stuff, no worries -- just wanted to ensure you weren't waiting for something on my part.