Use `external` plugin

index.html

@@ -53,6 +53,12 @@
                     config: 'TeX-AMS_HTML-full'  // See http://docs.mathjax.org/en/latest/config-files.html
                 },
                 dependencies: [
+                    {
+                        src: './reveal.js/plugin/external/external.js',
+                        condition: function() {
+                            return !!document.querySelector( '[data-external],[data-external-replace]' );
+                        }
+                    },
                     {
                         src: './reveal.js/plugin/markdown/marked.js',
                         condition: function () {
@@ -88,14 +94,14 @@
 
 <div class="reveal">
 	<div class="slides">
-		<section data-markdown="./slides/intro.html"></section>
+		<section data-external-replace="./slides/intro.html"></section>
 		<section data-charset="utf-8"
 		         data-markdown="./slides/content.md"
 		         data-separator="^\r?\n---\r?\n$"
 		         data-separator-notes="^Notes:"
 		         data-separator-vertical="^\r?\n----\r?\n$">
 		</section>
-		<section data-markdown="./slides/outro.html"></section>
+		<section data-external-replace="./slides/outro.html"></section>
 	</div>
 </div>
 

reveal.js @ 9fb68a17

-Subproject commit 5fe65260da01394ddf76dfb7c1cc260678178a40
+Subproject commit 9fb68a1713a5c0fb62ba0e2d3bca1ec9b3573de6