Add schema.org/BreadcrumbList support (grossss)

templates/default-layout.hamlet

@@ -12,12 +12,13 @@
                         <li .nav-item :Just route == mcurrentRoute:.active>
                             <a .nav-link href=@{route}>#{label}
 
-    $if not $ null parents
-        <ul .breadcrumb>
-            $forall bc <- parents
+    $if not $ null crumbs
+        <ol .breadcrumb>
+            $forall (route, title) <- crumbs
                 <li .breadcrumb-item>
-                    <a href=@{fst bc}>#{snd bc}
+                    <a href=@{route}>#{title}
             <li .breadcrumb-item.active>#{title}
+        <script type="application/ld+json">#{preEscapedToMarkup jsonCrumbs}
     $maybe msg <- mmsg
       <div .alert.alert-info #message>#{msg}