Added 3-level deep nesting test

Fixes #42

mustache.js

@@ -610,5 +610,4 @@ var Mustache;
   }
 
   return exports;
-
 }())));

test/_files/grandparent_context.js

@@ -0,0 +1,19 @@
+({
+  grand_parent_id: 'grand_parent1',
+  parent_contexts: [
+    {
+      parent_id: 'parent1',
+      child_contexts: [
+        { child_id: 'parent1-child1' },
+        { child_id: 'parent1-child2' }
+      ]
+    },
+    {
+      parent_id: 'parent2',
+      child_contexts: [
+        { child_id: 'parent2-child1' },
+        { child_id: 'parent2-child2' }
+      ]
+    }
+  ]
+})

test/_files/grandparent_context.mustache

@@ -0,0 +1,10 @@
+{{grand_parent_id}}
+{{#parent_contexts}}
+{{grand_parent_id}}
+{{parent_id}}
+{{#child_contexts}}
+{{grand_parent_id}}
+{{parent_id}}
+{{child_id}}
+{{/child_contexts}}
+{{/parent_contexts}}

test/_files/grandparent_context.txt

@@ -0,0 +1,17 @@
+grand_parent1
+grand_parent1
+parent1
+grand_parent1
+parent1
+parent1-child1
+grand_parent1
+parent1
+parent1-child2
+grand_parent1
+parent2
+grand_parent1
+parent2
+parent2-child1
+grand_parent1
+parent2
+parent2-child2