Breaking changes, rewrite; add support for plain text output and single page mode

exampleSite/content.en/book/index.md

@@ -0,0 +1,7 @@
+---
+title: Single Page
+layout: book
+menu:
+  after:
+    weight: 7
+---

exampleSite/content.en/docs/shortcodes/tests.md

@@ -17,7 +17,7 @@ bookHidden: true
   {{<button href="/">}}A Button{{</button>}}
 
 - ## Card
-  {{<card href="/docs/shortcodes/cards">}}
+  {{<card href="/docs/shortcodes/experimental/cards">}}
   **Markdown**  
   Suspendisse sed congue orci, eu congue metus. Nullam feugiat urna massa.
   {{</card>}}

exampleSite/content.en/posts/_index.md

@@ -1,6 +1,6 @@
 ---
+title: Blog
 menu:
   after:
     weight: 5
-title: Blog
 ---