test: add issue 467 test

dist/showdown.js

@@ -1,4 +1,4 @@
-;/*! showdown v 1.8.2 - 23-11-2017 */
+;/*! showdown v 1.8.2 - 28-11-2017 */
 (function(){
 /**
  * Created by Tivie on 13-07-2015.

test/issues/#467.header-ids-for-subheadings.html

@@ -0,0 +1,5 @@
+<h2 id="headeridinh2">header id in h2</h2>
+<h3 id="headeridinh3">header id in h3</h3>
+<h4 id="headeridinh4">header id in h4</h4>
+<h5 id="headeridinh5">header id in h5</h5>
+<h6 id="headeridinh6">header id in h6</h6>

test/issues/#467.header-ids-for-subheadings.md

@@ -0,0 +1,9 @@
+## header id in h2
+
+### header id in h3
+
+#### header id in h4
+
+##### header id in h5
+
+###### header id in h6