Add conversion utilities for external highway datasets

[rsavoye]

In order to properly conflate highway data with OSM, the tagging schema needs to be the same. These simple utility programs convert the US Government highway data for National Forests. MVUM is for 4x4 highways mostly, RoadCore is all the roads. The data is similar though, but useful to compare when there is confusion. Most of the tagging in the original source is ignore, only the name, USFS reference number, surface, smoothness are preserved. While this can be done manually, it's more useful to automate the process as it works better with large files.