Make IMPLICIT ITERATORS a first class feature.

Closes #39.

examples/array_of_partials_implicit_partial.html

@@ -1,5 +1,4 @@
 Here is some stuff!
-{{%IMPLICIT-ITERATOR}}
 {{#numbers}}
 {{>partial}}
 {{/numbers}}

examples/array_of_strings.html

@@ -1,2 +1 @@
-{{%IMPLICIT-ITERATOR}}
 {{#array_of_strings}} {{.}} {{/array_of_strings}}

examples/array_partial.2.html

@@ -1,6 +1,4 @@
 Here's a non-sense array of values
-
-{{%IMPLICIT-ITERATOR}}
 {{#array}}
 	{{.}}
 {{/array}}

examples/array_partial.txt

@@ -1,6 +1,4 @@
 Here's a non-sense array of values
-
-
 1
 2
 3

mustache.js

@@ -260,8 +260,11 @@ var Mustache = function() {
     create_context: function(_context) {
       if(this.is_object(_context)) {
         return _context;
-      } else if(this.pragmas["IMPLICIT-ITERATOR"]) {
-        var iterator = this.pragmas["IMPLICIT-ITERATOR"].iterator || ".";
+      } else {
+        var iterator = ".";
+        if(this.pragmas["IMPLICIT-ITERATOR"]) {
+          iterator = this.pragmas["IMPLICIT-ITERATOR"].iterator;
+        }
         var ctx = {};
         ctx[iterator] = _context;
         return ctx;