- added Trainer.dart
  - initialize trainer with net:
      var trainer = new Trainer(net);
  - you can add trainingcases to the trainer
      trainer.addTrainingCase([-1, 1], [ 1]);
  - can tell to let the trainer train the added cases and
    the maximumReapeatingCycle (will train all the added cases x1000)
    and the precision
      trainer.trainOnlineSets(1000, .1);
  - precision decides how close the result has to be to the expected numbers
  - can print added trainingsets in ordeer to save and load them