Fixes
Switch to using settrace internally.

  There are some changes to the interface.

  Options formerly passed to trace_on now to go the Tracer's constructor

  The list of items to trace now must all be functions, added the 'all'
  function to expand a class/module into all its functions, and 'mapcat'
  to help process a list of classes/modules into a big list of
  functions.

  Should be a lot more difficult now for trace to break the environment
  in which it is running, since it no longer replaces or otherwise
  mutates the functions it is tracing.