.iteritems is depricated in Python3

[Christopher Coogan]

for k, v in lookup.iteritems():

in make_roi_mesh() utilizes dict.iteritems() which is deprecated in Python3.

for k, v in lookup.items():

works and is backwards compatible.

[Brittany Scheid]

^^
I ran into a similar issue with raw_input being deprecated in Python3 for img_pipe.py

This could be addressed by adding from six.moves import input and replacing all instances of raw_input with input