Separate formatting

[JoeBengalen]

In the Handler\AbstractHandler there is an interpolation function which does some formatting. Would it be nice to be able to register some separate formatters to do some stuff? Or would this be overkill.

[JoeBengalen]

Question is whether this belongs to the handler or to the message itself. Or should each do a part?

placeholder replacements could be done by the message class or the logger class, but specific formatting like casting an exception to a string and append it to the message is handler specific.

[JoeBengalen]

This will not be included in version 1.0.0 as it requires lots of work. I wanna keep the first release a simple a possible.