title: overlapping shape and character in ggplot legend
body: <p>When I plot points and text with the same colour, the <code>a</code> and the shape overlap in the legend.</p>
  
  <p>Can I tell ggplot not to draw the <code>a</code> in the legend? How?</p>
  
  <pre><code>M &lt;- data.frame(t=letters[1:16],
              xx=runif(16),
              yy=runif(16),
              g=rep(c("A","B","C","D"),4))
  str(M)
  
  ggplot(M,aes(x=xx,y=yy,label=t,colour=g)) + 
         geom_point(shape=3) + 
         geom_text(vjust=0,hjust=0) + 
         scale_colour_discrete()
  </code></pre>
  
  <p><img src="https://i.imgur.com/kE1glQb.jpg?1" alt=""></p>