update numpydoc to 0.5-dev; rename section "Instance Variables" to "Attributes"

doc/sphinxext/LICENSE.txt

doc/sphinxext/__init__.py

doc/sphinxext/numpydoc/__init__.py

doc/sphinxext/numpydoc/comment_eater.py

doc/sphinxext/numpydoc/compiler_unparse.py

doc/sphinxext/numpydoc/docscrape.py

doc/sphinxext/numpydoc/docscrape_sphinx.py

doc/sphinxext/numpydoc/linkcode.py

doc/sphinxext/numpydoc/numpydoc.py

doc/sphinxext/numpydoc/phantom_import.py

doc/sphinxext/numpydoc/plot_directive.py

doc/sphinxext/numpydoc/tests/test_docscrape.py

doc/sphinxext/numpydoc/tests/test_linkcode.py

doc/sphinxext/numpydoc/tests/test_phantom_import.py

doc/sphinxext/numpydoc/tests/test_plot_directive.py

doc/sphinxext/numpydoc/tests/test_traitsdoc.py

doc/sphinxext/numpydoc/traitsdoc.py

kwant/builder.py

kwant/lattice.py

kwant/physics/leads.py