inputs: jump_model - a model object containing that has been previously solved.
description: fixes the iteger variables ones the model has been solved in order to calculate approximations of dual variables
returns: none (modifies an existing-solved model in the memory). solve() must be run again to solve and getdual veriables
inputs: EP - a JuMP model representing the energy optimization problem setup - a Dict containing GenX setup flags
description: Solves and extracts solution variables for later processing
returns: results EP model object with a set of DataFrames containing key results