title: Add points to the existing matplotlib scatter plot
body: <p>How to add points to the existing diagram? The straightforward solution is to plot a new scatter, adding new data. </p>
  
  <pre><code>ax.scatter(data[:,0], data[:,1], cmap = cmap, c = color_data)
  ax.scatter(new_points_x, new_points_y, color='blue')
  </code></pre>
  
  <p>But if we want to add more points with new colors, there is a problem: we have to take into consideration all previously added points. </p>
  
  <p>It would be great if I could use a special function like</p>
  
  <pre><code>AddPoint(ax, new_point, color)
  </code></pre>
  
  <p>I want only add new points in new colors. I do NOT need any animations</p>