title: GDI+: Set all pixels to given color while retaining existing alpha value
body: <p>What is the best way to set the RGB components of every pixel in a <code>System.Drawing.Bitmap</code> to a single, solid color? If possible, I'd like to avoid manually looping through each pixel to do this.</p>
  
  <p>Note: I want to keep the same alpha component from the original bitmap. I only want to change the RGB values.</p>
  
  <p>I looked into using a <code>ColorMatrix</code> or <code>ColorMap</code>, but I couldn't find any way to set all pixels to a specific given color with either approach.</p>