untested thread specify support

[ragesoss]

@kjschiroo

Traceback (most recent call last):
  File "/usr/lib/python3.5/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.5/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/sage/play/TopicContribs/topics/cmdline.py", line 68, in <module>
    main(arguments)
  File "/home/sage/play/TopicContribs/topics/cmdline.py", line 61, in main
    dump_paths, cohorts, pages, threads=args["--threads"]
  File "/home/sage/play/TopicContribs/topics/extract.py", line 33, in analyse_dumps
    for sub_res in mwxml.map(_partial, dumps, threads=threads):
  File "/usr/local/lib/python3.5/dist-packages/mwxml-0.2.2-py3.5.egg/mwxml/map/map.py", line 49, in map
  File "/usr/local/lib/python3.5/dist-packages/para-0.0.5-py3.5.egg/para/map.py", line 77, in _map_many_items
TypeError: unorderable types: str() > int()

[kjschiroo]

That seems right.