Hi for all

What do you think about new methods in Logger interface for kotlin/scala developers?

We want to use
        logger.trace { "Message with $parameter" }
instead of
        logger.trace("Message with {}", parameter)

It will be allowed when methods like

	default void trace(Supplier<String> msgSupplier) {
	    if (isTraceEnabled()) {
	        trace(msgSupplier.get());
	    }
	}

will be added info org.slf4j.Logger interface.

I've done the first part of this in https://github.com/qos-ch/slf4j/pull/253 and I will to done all of this if someone want to review.