golden_section: FW Equilibrium assignment
In douglascm/trafficr: Traffic Assignment Methods

The golden-section search is a technique for finding the extremum of a strictly unimodal function by successively narrowing the range of values inside which the extremum is known to exist. For more details please refer to: https://en.wikipedia.org/wiki/Golden-section_search Initial params, notice that in our case the optimal theta must be in the interval [0, 1]

1	golden_section(flow, auxiliary_flow, graph, accuracy = 1e-08)

`flow`	Past iteration calculated traffic flow
`auxiliary_flow`	Current iteration calculated traffic flow
`graph`	Graph object created with configure_graph() function
`accuracy`	Golden section accuracy value. The accuracy is suggested to be set as 1e-8.