title: how to use spread.labels
body: <p>I have points on the map that are very close to each other and I would like to separate the labels because they are overlapping. I want to use spread.labels command, but I get an error smth along this line:  </p>
  
  <pre><code>Error in text.default(newx, y + offsets, labels[sort.index], srt = srt,  : plot.new has not been called yet  
  
    mp = get_map(location = "Canada", maptype="satellite", color="color")
  p = ggmap(mp) +
    geom_point(data=df1, aes(x=decLon, y = decLat), color="red", size=2.6) +
    spread.labels(x=df1$decLon, y=df1$decLat, label=df1$Site, offsets=0.5)
  p   
  </code></pre>