title: matplotlib legend: Including markers and lines from two different graphs in one line
body: <p>I've been doing some linear regression and want to plot the markers (original data) and the lines (regression) on the same line in the legend. For simplicity, here's a fake regression:</p>
  
  <pre><code>from pylab import *
  ax = subplot(1,1,1)
  p1, = ax.plot([1,2,3,4,5,6],'r-', label="line 1")
  p2, = ax.plot([6,5,4,3,2,1],'b-', label="line 2")
  
  p3, = ax.plot([1.2,1.8,3.1,4.1,4.8,5.9],'ro', label="dots 1")
  p4, = ax.plot([6.1,5.1,3.8,3.1,1.9,0.9],'bo', label="dots 2")
  
  ax.legend(loc='center right',numpoints=1)
  show()
  </code></pre>
  
  <p>So I want the legend to consist of 2 lines, each showing a line and a dot, instead of 4 lines. How can I do that?</p>