- rewriting backprop algorithm; the code is an order of magnitude
  cleaner than the last one
- first learning test passes
- the network is learning, but learning multiple patterns is not
  working
- I think I found a bug...
- wrote "x-ray" function which provides a full dump of a neural
  network
- it's learning, but something seems wrong with my format in
  matrix_test.scm
- IT'S LEARNING!!!!!!!!
- updated project_log.txt
- fixed the printing, but left a commented section so I can investiate
  that bug: format was printing a duplicate value in the ~A field, so
  I thought that the neural net was returning the exact same thing
  each time