a new way of building -- this works for python 2 or 3 well
make this work with python3 -- had to do list(dict.keys()) because
python3 has a dict_keys object.
fix some imports for python3
get this working with python 3.x
update for python3
python 3-ing
python3-ed
python3-ed
more PEP-8
some more comments
a notebook that illustrates how to use the mesh.

Also change the behavior of pretty_print() to be more inline with
our expectations -- now (0,0) is at the lower left.
use init_zeros()
start of a notebook
rename multigrid.py to MG.py to avoid the potentially problematic
import multigrid.multigrid when sitting in multigrid/
multigrid -> MG
a notebook version of mg_test.py
fix some typos in a docstring
use qx and qy
fix comment
fix another comment