Use nocache when fetching diagrams

This way correct cache headers are set. Default is 1 hour, so some
browsers wouldn't immediately show changes in recently edited diagrams.

Author: annda

syntax.php

@@ -58,6 +58,7 @@ public function render($format, Doku_Renderer $renderer, $data)
         $renderer->doc .=
             '<object data="'
             . ml($data['src'])
+            . '&cache=nocache'
             .'" type="image/svg+xml" class="diagrams-svg media'
             . $data['align']
             .'" ></object>';