Tag OpenStreetMap v0.3.0

Added capability to classify streets, buildings, and features from the map, and display this in plots. "Layers" are used to define color schemes and plotting styles, and a standard layer is defined for each map category. This allows plotting maps similar to the OpenStreetMap web interface, which shows different road classifications (e.g., freeways vs. residential streets) as having different widths and colors.

Also added the capability to extract walkways (pedestrian-friendly routes) and cycleways (bicycle-friendly routes) and plot them as map layers.