Ensured arrays were documented.
Fixed issue with initialization of Lbfgsb bounds fields.

* Replaced initialization of Lbfgsb bounds fields (slices) with
  initialization of local bounds slices.  The Lbfgsb slice fields can be
  nil, and initialization must not overwrite those values as was
  happening.
* Added function to make C-type copies of Go slices.
* Added another optimization to the example program which reuses an
  optimizer.  This is what uncovered the issue.
* Improved the example program by adding comments, naming objects for
  reuse, making values less uniform.
* Added debugging output and left it in in case it comes in handy later,
  like for when I actually add some debugging features.
Implemented logging functionality in Go files.

* Added optimization iteration logging function type to API.
* Added container for optimization iteration information with some basic
  methods for printing.
* Added logging functionality to Lbfgsb object including setter.
* Implemented logging function callback machinery that had only been
  stubbed.
* Completed logging example in example program.
Moved logging callback to separate helper function.

* Added error message to accompany error status.
Removed C string lengths from internal Fortran routines.

* Fortran keeps track of its array sizes so lengths of C character
  arrays do not need to be passed around between Fortran routines.
Added status constants to C API.

* Removed old TODO about logging.
Removed TODOs about panics.

* Decided to let panics propagate through C/Fortan because there is
  really nothing the the callbacks can do to handle them and because
  then Go can collect a full stack trace.  (The alternative, converting
  the panics to returning error codes, loses information and interrupts
  Go's panic handling.)  This might result in improper cleanup in
  C/Fortran.  However, everything in C/Fortran is on the stack at the
  moment, so at least there should not be memory leaks.  Also, I'm not
  sure how to do proper C/Fortran cleanup without the ability to
  register a panic handler with the Go runtime.