Render persistence data before form output changed to work with populated fields.

persistent_multipage_forms-reloaded.php

```php
// Render persistence data before form output
add_filter("gform_pre_render", "ri_pre_populate_the_form");
function ri_pre_populate_the_form($form) {
    if (gfdp_is_persistent($form)) {
		$current_page = GFFormDisplay::get_current_page($form["id"]);
		if ($current_page == 1) {
			$option_key = ri_getFormOptionKeyForGF($form);
			if (get_option($option_key)) {
				$persistent_info = json_decode(get_option($option_key));
				//start new code
				// For every field in form we have to check if populate is active, if so, grab inputName value (=$_GET value). If its not empty use that for default field value.
				foreach ($form['fields'] as $_field) :
					if (isset($_field['allowsPrepopulate']) && $_field['allowsPrepopulate']) :
						$get_key = $_field->inputName;
						if (isset($_GET[$get_key]) && !empty($get_key)) :
							$field_id = ($_field->id) ? $_field->id : '' ;
							if ($field_id && isset($persistent_info->{'input_'.$field_id})) :
								$persistent_info->{'input_'.$field_id} = sanitize_text_field($_GET[$get_key]);
							endif;
						endif;
					endif;
				endforeach;
				// end new code
				
				$persistent_info = json_encode($persistent_info);
				$_POST = json_decode($persistent_info, true);
			}
		}
    }	
    return $form;
}