Revised printing and debugging control.

* Removed debug level because it was not used for debugging as
  evisioned.
* Replaced with more transparent print control to control the Fortran
  output through the original L-BFGS-B API.
* Actual debugging features may be added again in the future.
* Print control may be removed in the future in favor of a logging API.
Go formatted.
Added logging to C-Fortran code.

* Information about each optimization iteration can now be logged by
  providing a callback to the Fortran code.  If specified, the callback
  is invoked at the end of every iteration with a bunch of information
  that one might like to log.
* Reordered status arguments to be last.