Takes a list of highways names which must enclose an internal area, and returns
a SpatialLines object containing a sequence of OSM nodes which cyclically
connect all highways. Will fail if the streets do not form a cycle.
A vector of highway names passed directly to the Overpass
API. Wildcards and whitespaces are '.'; for other options see online help for
the overpass API.
bbox
The bounding box within which to look for highways. Must be a
vector of 4 elements (xmin, ymin, xmax, ymax).
plot
If TRUE, then all OSM data for each highway is plotted and the
final cycle overlaid.
Value
A single data.frame containing the lat-lon coordinates of the cyclic
line connecting all given streets.