Major directive refactor (#195)

Fixes #188 #144 #76: major refactor of directive parsing, rendering, styling

plugs/markdown/markdown_render.ts

@@ -362,6 +362,10 @@ function render(
         body: cleanTags(mapRender(newChildren)),
       };
     }
+    case "Directive": {
+      const body = findNodeOfType(t, "DirectiveBody")!;
+      return posPreservingRender(body.children![0], options);
+    }
     // Text
     case undefined:
       return t.text!;