MPI improvements from EuXFEL experiment

[phyy-nx]

• Add parameter output_debug_logs = True. Controls whether to write debugging information for every image. These are the .txt files in the debug folder that help with diagnostics, but when running on 7K cores, they stress the file system too much.
• Move instantiation of the Processor object. Before it was in the if/else of the MPI client/server code. Now, each process creates a Processor object before client/server, then calls finalize on the object after client/server. This allows downstream applications (like the XFEL GUI) to put synchronization code in the __init__function of the Processor.