Color customization

[topi314]

This pr adds the ability to customize the color of nearly all elements of a log line.
I don't expect this pr to necessarily get merged, but I figured it would be worth trying since that's what I, as a user want. In case this does not get merged I can just keep maintaining my fork no problem.

I made sure the current log colors are the default. If wanted I could add a new predefined default theme, but I don't think this is necessary. I'm open to address any feedback

The following different kind of thing can be colorized in a log line (it is sorted in order of their usual appearance):

const (
	KindTime Kind = iota
	KindSourceFile
	KindSourceSeparator
	KindSourceLine
	KindMessage
	KindGroup
	KindKey
	KindSeparator
	KindValue
	KindErrorKey
	KindErrorSeparator
	KindErrorValue
)

[topi314]

I also changed tint.Err to not return a tintError since that's a weird behavior imo.
If let's say a library logs an error, the error is not being logged red unless they also depend on the tint module which is really annoying

[lmittmann]

I also changed tint.Err to not return a tintError since that's a weird behavior imo.

If let's say a library logs an error, the error is not being logged red unless they also depend on the tint module which is really annoying

That's a feature. It allows you to use different handlers in different environments, e.g tint in dev and slog's JSON handler in prod. You don't want your json log to contain ansi codes.

[topi314]

I'm not sure why this is needed then, I already use the json handler for production and I don't have any ansi codes in my production logs

[lmittmann]

It is needed because tint should not print every error in red color, but only those wrapped in tint.Err(...). And errors wrapped in tint.Err(...) should just be "normal" errors to all the other handlers.

[lmittmann]

Thank's for the effort, but I will not merge the changes. tint provides an opinionated output format, that can be customized to some extend via Options.ReplaceAttr (e.g. change level colors), or can be forked to tailor the output format to your liking. Also this PR degrades performance quite a lot.