Provide an option to print evaluation trace

[anderseknert]

While the current logging is good for extensive debugging or Jarl, it is way too noisy for it to be useful for debugging the IR. It would be cool if we could build a tracing logger that would output two "columns", where the first one contains lines of the commands being run, and the next column contained the current state worked on.

It would help if the left column got intented for each level of nesting, so that one can more easily discern where in the call chain the current position is.

While we could use the logging framework for this, the formatting of the messages should not contain anything but the data (i.e. no timestamps, etc).