added query string variable csv-year for the csv exports that need to…

… filter by year

mfo-base.php

@@ -517,6 +517,7 @@ function crlf_shortcode( $atts, $content = null ) {
 function custom_rewrite_tag() {
   //https://codex.wordpress.org/Rewrite_API/add_rewrite_rule
   add_rewrite_tag('%csv-filename%', '([^&]+)');
+  add_rewrite_tag('%csv-year%', '([^&]+)');
 }
 
 add_action('init', 'custom_rewrite_tag', 10, 0);