Implemente sequence operator on signal class.

Reviewer: Hugo Parente Lima <hugo.lima@openbossa.org>,
          Luciano Wolf <luciano.wolf@openbossa.org>

libpyside/qsignal.h

@@ -14,9 +14,17 @@ typedef struct {
     char *signal_name;
     char **signatures;
     int signatures_size;
-    PyObject *source;
 } SignalData;
 
+typedef struct {
+    PyObject_HEAD
+    char *signal_name;
+    char *signature;
+    PyObject *source;
+    PyObject *next;
+} SignalInstanceData;
+
+
 extern "C"
 {
     PyAPI_DATA(PyTypeObject) PySideSignal_Type;