title: Getting color of a data series from a flot chart
body: <p>After seeing the cool new "reputation" tab on the stackoverflow user page, I was inspired to play with the Flot charting library a little.  I have a line chart that has several hundred series.  Only a couple of these series will be visible at any given time.  My data series are grouped into several "categories" and I assign the numeric color index based on that category.  I'd like to be able to see what actual color was assigned by Flot to a particular color index value, for the ultimate purpose of creating a custom legend that relates the color to my "category" of data.  How can I get these color values?</p>
  
  <p>I see that I can provide my own array for colors, but I am reluctant to do this, because I am not sure how many categories I will have until I load the data.  I suppose I could just create an array that's just <em>way</em> too big, but that seems wasteful if it's possible to ask Flot what color each series is.</p>