Re-create scan.py as node idea in which each of nodes has parents and/or children.
Change xml format and list format.
Modified doctest.
add docstring and doctest.
infomanager.py is splited between the funcftion 'humanReadable' and others.
details of read and save xml files in infomanage.py are moved to etreeio.py.
Refactoring.
Rename some function and Update doctest.
Rename to lowercase with underscore.
Pipe must return node_list about issue #5
Split off the directory generation about issue #3

Spilt off the directory generation part from doctest,
since it is not concerned manipulation.
Small fix about coding style (issue #3)
Fix walking order (issue #3)
Fix doctest reflecting the sorting (issue #3)
Implement node_list to/from JSON interface
Implement register function
Remove same functional pipe as jsonio.py
Fix small bug
Add file check
split line for limitation of line length.