Add a failing test for #167

Multiple levels of nested partials are only indented to the level of the first partial.

test/fixtures/examples/nested_partials/NestedPartials.php

@@ -0,0 +1,6 @@
+<?php
+
+class NestedPartials
+{
+    public $val = 'FOURTH!';
+}

test/fixtures/examples/nested_partials/nested_partials.mustache

@@ -0,0 +1,3 @@
+<first>
+  {{> second }}
+</first>

test/fixtures/examples/nested_partials/nested_partials.txt

@@ -0,0 +1,7 @@
+<first>
+  <second>
+    <third>
+      FOURTH!
+    </third>
+  </second>
+</first>

test/fixtures/examples/nested_partials/partials/fourth.mustache

@@ -0,0 +1 @@
+{{ val }}

test/fixtures/examples/nested_partials/partials/second.mustache

@@ -0,0 +1,3 @@
+<second>
+  {{> third }}
+</second>

test/fixtures/examples/nested_partials/partials/third.mustache

@@ -0,0 +1,3 @@
+<third>
+  {{> fourth }}
+</third>