create_map: Create map
In informalr/informalr: Learn R Informally in a Team

Fetch a map of Groningen from OpenStreetMap and save it as a PNG-file.

create_map(
  png_filename,
  show_bridge_openings = "yes",
  right_lon = 1,
  left_lon = 2,
  top_lat = 3,
  bottom_lat = 4
)

`png_filename`	name of the PNG that the map will be saved to
`show_bridge_openings`	character string indicating whether or not bridge openings are plotted on top of the basemap. The default, `"yes"` adds the real time bridge openings to the map. `"fake"` adds one fake bridge opening in the center of Groningen. `"no"` does not add any bridge openings to the map.
`right_lon`	right longitude
`left_lon`	left longitude
`top_lat`	top latitude
`bottom_lat`	bottom latitude