Fix for Auto Generated Avatar Image when Letters not Centered

Issue is with older MS Edge browser. Now return png instead of svg. Once issue fixed by image provider should revert back to svg.

See: LasseRafn/ui-avatars#37 (comment)

system/lib-user.php

@@ -582,8 +582,9 @@ function USER_generateUserICON($uid, $width = 0, $cssClasses = '', $anonName = '
             $text_color = _textColorBasedOnBgColor($bg_color, 'FFFFFF', '000000');
             // See https://ui-avatars.com/ for API
             // See https://github.com/LasseRafn/php-initial-avatar-generator and https://github.com/LasseRafn/ui-avatars for github libraries
+			// Fix Letter offset issue for MS Edge 11. Specify png instead of default svg. See https://github.com/LasseRafn/ui-avatars/issues/37#issuecomment-688314690 (Note: Should set back to svg once issue fixed)
             $extrasettings = PLG_getThemeItem('core-auto-generated-user-avatar-settings', 'core');
-            $retval = '<img src="https://ui-avatars.com/api/?name=' . $letters . '&color=' . $text_color . '&background=' . $bg_color . '&size=' . $_CONF['max_photo_width']
+            $retval = '<img src="https://ui-avatars.com/api/?name=' . $letters . '&color=' . $text_color . '&background=' . $bg_color . '&size=' . $_CONF['max_photo_width'] . '&format=png'
                 . $extrasettings . '"  alt="" title="' . $altText . '" class="' . $cssClasses . '"';
             if ($width > 0) {
                 // Since a square is returned set height as well