mostly removing of nodes from the graph.
One result lost:
```
check("submodule.submodule_attr", submodule.submodule_attr, "submodule_attr", globals()) #$ MISSING:prints=submodule_attr
```
Dataflow, points-to, call-graph and type-inference tests.
Since dataflow, points-to, call-graph and type-inference are all interlinked it makes sense to test them together.
The test code.
The test code is all under the code/ subdirectory and all test files are named \w_name, supporting
files do have an underscore as their second character.
This allows tests to be applied to a subset of the test data and test/data combinations to be turned on/off easily for debugging.
Be aware that here are two __init__.py, so the results are interleaved.