Creates an interactive map plot.
The input can be either an object of the class "map" passed
directly to the x parameter or two vectors of matching
coordinates passed to x and y. The format for polygons
in the same as used by the map function.
Each polygon should correspond to a case and it will be linked
correspondingly. See ivar.new.map for details on map
variables.
Note: this function is currently experimental and it may change in the
future.