added formatting to verbose and logfile, fixed multiprocessing porblem and GPU usage in analysis_example

[gwirn]

• README added conda install instruction to manual installation guide in the README
• environment.yml added openmmtorchplugin
• analysis_example added main function and if __name__ == "__main__" to avoid multiprocessing error, and added sending the net to the GPU as well as always choosing GPU if one is available instead of manually
• trainer prettier formatting in the verbose training setting like

  train_mse_loss     : 0.003045
  train_physics_loss : 21369.562486
  train_loss         : 0.003349
  valid_mse_loss     : 0.003196
  valid_physics_loss : 22197.075703
  valid_loss         : -4.763431
  train_seconds      : 9.927747
  valid_seconds      : 0.528163
  checkpoint_seconds : 0.256874
  total_seconds      : 10.712785

  and formatting of the log file so it can easily be read with eg pandas.read_csv