merge ri_seq into ri_widget

change image file location in interface.xml, and change python file to use relative file location for it.

python/ri_seq.py

@@ -0,0 +1,42 @@
+#!/usr/bin/python
+
+class Sequence:
+    ''' implement sequence in interface xml'''
+    dict={}
+
+    def __init__(self, xml_node):
+        self.steps = [ s.attributes["name"].value for s in xml_node.childNodes
+                 if s.nodeType == s.ELEMENT_NODE and s.nodeName == "widget" ]
+        self.current_step = 0
+
+    def set_current_step(self, st):
+        ''' set current step based on input step name'''
+        self.current_step = self.steps.index(st)
+
+    @staticmethod
+    def set_current_sequence(name):
+        Sequence.current_sequence = Sequence.dict[name]
+
+    @staticmethod
+    def current():
+        return (Sequence.current_sequence, Sequence.current_sequence.steps[Sequence.current_sequence.current_step])
+
+    @staticmethod
+    def previous():
+        if Sequence.current_sequence.current_step:
+            Sequence.current_sequence.current_step -= 1
+            return Sequence.current_sequence.steps[Sequence.current_sequence.current_step]
+
+    @staticmethod
+    def next():
+        if Sequence.current_sequence.current_step < len(Sequence.current_sequence.steps)-1:
+            Sequence.current_sequence.current_step += 1
+            return Sequence.current_sequence.steps[Sequence.current_sequence.current_step]
+
+def construct(xml_root):
+    ''' construct Sequence's static members'''
+    for s in xml_root.childNodes:
+        if s.nodeType == s.ELEMENT_NODE and s.nodeName == "sequence":
+            Sequence.dict[s.attributes["name"].value] = Sequence(s)
+
+