BREAKING CHANGES:
* Custom appenders that rely on the :more argument will no longer function correctly.
* Stacktraces are no longer automatically generated at the `log`-macro level, but are
left as an appender implementation detail. A :throwable appender argument has been added
along with a `stacktrace` fn.
MIGRATION GUIDE:
* :message is now a string of all arguments as joined by `logp`/`logf`. Appenders that
need unjoined logging arguments (i.e. raw arguments as given to `logp`/`logf`) should
use the new :log-args vector.
MOTIVATION:
The :more argument was always kind of manky.
By joining logging arguments at the `log`-macro level, we simplify appender
implementations and allow the use of different joining strategies like `logp` and
`logf`.
This approach also fits better with the `tools.logging` API, allowing a cleaner
Logger implementation.
* Appenders are now decorated via 2 separate mechanisms: a per-appender
decorator (as before), and a new per-juxt (i.e. combined) decorator.
The per-juxt wrapping provides a performance-conscious hook for
higher-level facilities like the new middleware feature.
* Moved compile-time config wrapping from per-appender to per-juxt,
improving performance.
* Fixed appender wrapper ordering.
All future appenders that depend on an external library will follow this pattern, allowing the
flexibility to add more diverse appenders without the worry of bloating Timbre core or Timbre's
dependencies.
See updated README example for how to include standard email appender.
