Add __iter__ for QgsFeature

Author: NathanW2

python/core/qgsfeature.sip

@@ -116,6 +116,12 @@ class QgsFeature
 
   public:
 
+    SIP_PYOBJECT __iter__();
+%MethodCode
+    PyObject *attrs = sipConvertFromType( &sipCpp->attributes(), sipType_QgsAttributes, Py_None );
+    sipRes = PyObject_GetIter(attrs);
+%End
+
     SIP_PYOBJECT __getitem__(int key);
 %MethodCode
   const QgsAttributes& attrs = sipCpp->attributes();