Di/Graph: Allow JSON file in the constructor.
algorithms/operators: Improve performance
algorithms.diff: Add method to clear up clutter.
Rename diff_eg.py -> diff.py
examples/diff.py: Add -u flag. Default out name change.
Graph: Add neighbors()
DiGraph: Add predecessors()
Graph: Fix timeline export
Graph: Use sn.add_node() in load_json()
Graph: Fix tests for load_json()
Ignore tags and notes.
Add asn_example.
Add mergers example.
A U B should have attrs of B.
algorithms: Optional checks for attr modifications.
examples/diff: Add option for modifications.
Merge branch 'algorithms'

Add diffstatus 'modified'