Easier file tree for human.

Examples:

>>> from filetree import File
>>> f = File('.')
>>> f.files
[<file: .gitignore>, <file: LICENSE>, <file: Makefile>, <file: README.rst>, <file: setup.py>]
>>> f.dirs
[<dir: .git>, <dir: build>, <dir: dist>, <dir: docs>, <dir: filetree>]
>>> f.images
[<file: python-logo.png>, <file: favicon.jpg>]

API:

__call__
__iter__
__eq__

files
dirs
images
listdir

exists
type

is_blank
is_dir
is_file
is_hidden

info
atime
ctime
mtime

move_to
remove
remove_blank_dirs
remove_blank_subdir

size
walk