title: matplotlib scatter edge without specifying edgecolor
body: <p>It seems that now the default scatter plot marker is a filled circle without an edge. I want a marker with an edge and with facecolor="none".
  But if facecolor="none" but edgecolor is not specified, then the plot is empty.
  I want markers be in multiple distinct colors, but don't care which one has which color.</p>
  
  <p>How can I just "turn on" the edges? </p>