Print fitinfo to file
Created by: scarlehoff
This is addressing #988 (closed)
I thought that given that the stopping is already holding most of the information that we want in the .fitinfo
file it would make sense for the stopping to be dump-able to a dictionary/file. For now I've added the chi2s and the positivity status.
Please let me know whether you like this approach (and whether more important information is needed).