image_scale_and_crop should round $w and $h before calling image_gd_scale

Current implementation of image_scale_and_crop does not round target width and height when calling image_gd_resize. This results in the same problem described in http://drupal.org/node/271303. The proposed implementation is a port of the patch described in http://drupal.org/node/271303 to Drupal 6

Old:

function image_scale_and_crop($source, $destination, $width, $height) {
  $info = image_get_info($source);

  $scale = max($width / $info['width'], $height / $info['height']);
  $x = round(($info['width'] * $scale - $width) / 2);
  $y = round(($info['height'] * $scale - $height) / 2);

  if (image_toolkit_invoke('resize', array($source, $destination, $info['width'] * $scale, $info['height'] * $scale))) {
    return image_toolkit_invoke('crop', array($destination, $destination, $x, $y, $width, $height));
  }
  return FALSE;
}

New:

function image_scale_and_crop($source, $destination, $width, $height) {
  $info = image_get_info($source);

  $scale = max($width / $info['width'], $height / $info['height']);
  $x = round(($info['width'] * $scale - $width) / 2);
  $y = round(($info['height'] * $scale - $height) / 2);
  $scaled_w = round($info['width'] * $scale);
  $scaled_h = round($info['height'] * $scale);
  if (image_toolkit_invoke('resize', array($source, $destination, $scaled_w, $scaled_h ))) {
    return image_toolkit_invoke('crop', array($destination, $destination, $x, $y, $width, $height));
  }
  return FALSE;
}

Patch file to be submitted when I have access to my development machine