title: Rgooglemaps not plotting data over the map
body: <p>I am having an issue with the R package Rgooglemaps. I can retrieve a map from google maps or open street map but the PlotOnStaticMap function does not overlap the data I want to plot to the map. Instead it opens a new graphical device where it plots the data. So I end up with:</p>
  
  <ul>
  <li>an image saved in my working dir which contains only the retrieved google map</li>
  <li>a R graphic device window with my data plotted over a white background.</li>
  </ul>
  
  <p><p>I am on windows, using R version 2.13.1 and RGUI. The issue appears also when I run the code via command line. I remember I used Rgooglemaps a few months ago and it worked properly for me. Meanwhile I upgraded my R version, so it could be a version related issue.</p> <p>Can someone give it a try and see if you have the same issue (and a way to solve it)?</p> Here an example to reproduce the issue (taken from <a href="http://www.r-bloggers.com/visualizing-gis-data-with-r-and-open-street-map/" rel="nofollow">http://www.r-bloggers.com/visualizing-gis-data-with-r-and-open-street-map/</a>). The example is using Open Street Map instead of googlemaps but the behavior is the same.
  The code:</p>
  
  <pre><code>require(RgoogleMaps)
  lat_c&lt;-51.47393
  lon_c&lt;-7.22667
  bb&lt;-qbbox(lat = c(lat_c[1]+0.01, lat_c[1]-0.01), lon = c(lon_c[1]+0.03, lon_c[1]-0.03))
  OSM.map&lt;-GetMap.OSM(lonR=bb$lonR, latR=bb$latR, scale = 20000, destfile="bochum.png")
  image(OSM.map)
  lat&lt;- c(51.47393, 51.479021)
  lon&lt;- c(7.22667, 7.222526)
  val &lt;- c(0, 255)
  lat_adj&lt;-function(lat, map){(map$BBOX$ll[1]-lat)/(map$BBOX$ll[1]-map$BBOX$ur[1])}
  lon_adj&lt;-function(lon, map){(map$BBOX$ll[2]-lon)/(map$BBOX$ll[2]-map$BBOX$ur[2])}
  PlotOnStaticMap(OSM.map, lat = lat_adj(lat, OSM.map), lon = lon_adj(lon, OSM.map),       
  col=rgb(255,0, val,90,maxColorValue=255),pch=16,cex=4)
  dev.print(jpeg,"test.jpeg", width=1204, height=644, units="px")
  </code></pre>