Add O.tags['id'] to header of batch log files and save terminal output during batch

What do you think about these ideas?
If you agree with them I could try to implement via github.

While adding some hints in batch documentation I saw that it is adviced to use the O.tag['id'] of each job for filename of logfiles and vtkfiles. I think it would be good to print the O.tag['id'] in the header of each job log file. This way you can easily assign a certain job to its related vtk files, plots, yade-saves.

Another nice feature would be a option for batch mode which enables terminal output logging. A 'global' logfile for all batch jobs of the current simulation could be created and terminal output copied inside. This way terminal output won't be lost.