title: matplotlib how to make a special marker
body: <p>I am trying to make a special marker which isn't available with the scatter command. I would like to make a "board pin" shape marker. In principle, arrow (under fancyarrow command) is fine but it doesn't allow me to use vmin and vmax option which is very crucial to me. Let's me explain. </p>
  
  <p>I have a set of <code>x, y</code> coordinates and velocities. The velocity is represented by the colorbar. Thus, reading in <code>x, y</code> and velocity and use scatter vmin and vmax command, the markers will be automatically plotted with the right color. eg:</p>
  
  <pre><code>f.show_colorscale(cmap="gist_hsv",vmin=0,vmax=8e3)
  f.scatter(x,y,c=vel,marker='o',s=50,vmin=0,vmax=8e3)
  </code></pre>
  
  <p>I only succeeded in plotting the "head" of the board pin (just a filled circle). Any idea how to get the "tail" of the board pin in various angle? </p>