Goal: "remote" tracebacks have file/lineno references to local source code

Current Problem: 
    tracebacks have file/lineno references that point to one
    large file (consisting of all source code of all modules that
    we sent as a bootstrap). Makes debugging execnet harder. 

solution variant 0: minimal change to source code 
    at master side: send name/source pairs 
    at slave side: put each module into own file, re-using basename of source file 

solution variant 1: aimed at simplicity 
    pack and send zip of py lib containing py.__.execnet, py.__.thread, etc 
    put this into some file-location at the other side, add it to sys.path 
    (or experiment with zipfile-imports over RAM and sys.meta_hooks/path_hooks) 

solution variant 2: aimed at minimizing bandwidth usage

    initiating side                     receiving side 
    -------------------------------------------------------------
                                 loop:
    send [dottedname1: hash1] 
    serve_hash_requests
                                        if not lookup(hash1):
                                            send(dottedname1: hash1)
                                            content =  receive(hash1) 
                                        else:
                                            content = get(hash1)