Tweaked by tabbott to not remove it from lister.py, linter_lib, and
friends, since those are intended to support both Python 2 and 3
(we're planning to extract them from the repository).
The js-dep-visualizer tool now attempts to find a set of edges
to remove from a call graph that would reduce it to having only
trivial mutual dependencies, and it produces a roadmap of the
changes that need to happen.
If the tool can't reduce the graph all the way, it still produces
a DOT file that can be visualized.
This fix also has some significant code cleanup.
This adds a report of nodes, handles some errors better, adds
some helpful output, cleans up some abspath calls, and
updates which modules and/or dependencies we temporarily are
ignoring for the report.