Restored hooke.plugin.macro from revision a008bd5c28ca.

Restored hooke.plugin.macro from revision a008bd5c28ca.

It had been removed in the subsequent commit:
  changeset:   519:928a1a2f6041
  branch:      wtk
  user:        W. Trevor King <wking@drexel.edu>
  date:        Sat Aug 07 11:45:12 2010 -0400
  files:       conf/macro.conf hooke/plugin/__init__.py hooke/plugin/macro.py
  description: Remove macro plugin.
  ...

In the commit comments, I explain that the hooke command line lacks
flexibility for function definition (e.g. no variables).  However, you
can do a number of things by chaining commands together, so I'm
bringing back the macro plugin.  I intend to reimagine macros as
editable "command stacks", which will allow for
* flexible loops
* undo/redo recent changes
* preserving processing through playlist save/load cycles.

This will get us most of the way to the goals expressed in commit
725a18055518 and a useful Hooke :).