dot notation support added

- all tests passing
- updated test to include check that it doesn't break IMPLICIT_OPERATOR
- added fix to ensure that you can access global context from within 'dot notatated' blocks

mustache.js

@@ -269,14 +269,17 @@ var Mustache = function() {
       }
 
       var value;
-      if(is_kinda_truthy(context[name])) {
-        value = context[name];
-      } else if(is_kinda_truthy(this.context[name])) {
-        value = this.context[name];
-      }
-
-  		if(name.match(/([a-z_]+)\.?/ig)){
-				value = this.walk_context(name, context);
+			
+			// check for dot notation eg. foo.bar
+			if(name.match(/([a-z_]+)\./ig)){
+				value = is_kinda_truthy(this.walk_context(name, context));
+			}
+			else{
+				if(is_kinda_truthy(context[name])) {
+	        value = context[name];
+	      } else if(is_kinda_truthy(this.context[name])) {
+	        value = this.context[name];
+	      }
 			}
 
       if(typeof value === "function") {
@@ -290,13 +293,15 @@ var Mustache = function() {
     },
 
 		walk_context: function(name, context){
-			var path = name.split('.')
-			var value_context = context;
-			var value = context[path.shift()];
+			var path = name.split('.');
+			// if the var doesn't exist in current context, check the top level context
+			var value_context = (context[path[0]] != undefined) ? context : this.context;
+			var value = value_context[path.shift()];
 			while(value != undefined && path.length > 0){
-				value_context = value
+				value_context = value;
 				value = value[path.shift()];
 			}
+			// if the value is a function, call it, binding the correct context
 			if(typeof value === "function") {
         return value.apply(value_context);
       }