Add RSP Evaluation Functionality

[tk-oleary]

The CMAP regionally significant project (RSP) evaluations include model runs to determine an RSP's transportation-related impacts on the travel network. For each RSP, a custom highway/transit network is created that includes the RSP itself, plus the existing transportation network, plus any additional projects that have already secured funding and/or are under construction (AKA "existing plus committed transportation projects"). We need a feature of MHN programs that will create networks for the RSP evaluation: for each RSP, the MHN will generate files that represent baselinks, completed projects, existing + committed projects, and the RSP itself.

This will involve editing "generate_highway_files" and "generate_transit_files" to select projects that have a completion year pre-2025, plus projects in a text file that represent "committed" projects, and select a project based on a number in an RSP parameter field (that is by default empty and ignored)