[#57744748] writers.to_xgmml has dynamic option

looks for 'start'/'end' or 'date' attributes in edges, and populates
start and end dates for nodes and edges. node/edge attack/delay options
allow for smoothing.
[#60554444] hacked away at bib parser to solve the most glaring errors

This is a long way from being great.
[#60554520] networks.simplify_multigraph

Simplifies a graph by condensing multiple edges between the same node
pair into a single edge, with a weight attribute equal to the number of
edges.
Merge branch 'erick' into python