Fix prefix 0s not correct for sequential file names starting at nonze…

…ro index

src/com/bensuniverse/WebsiteImageExtractor/ImageGrabber.java

@@ -232,7 +232,7 @@ private static BufferedImage resize(BufferedImage img, int max_width) {
     public void downloadImages(ArrayList<String> urls, String file_location, boolean rename, String prefix, String extension, int start_index, JProgressBar progress_bar, JPanel panel, JLabel status) {
 
         // get number of digits of total image count
-        int prefixNum = (int) Math.log10(urls.size());
+        int prefixNum = (int) Math.log10(start_index + urls.size()); // (start_index + urls.size()) in order to add 0 when not starting at 0
         System.out.println("prefixNum: " + prefixNum);
 
         // loop through each index of image list