Better scale management for order creation

+ Extends labels formatting of scale.

kfet/statistic.py

@@ -86,7 +86,10 @@ class Scale(object):
     def get_labels(self, label_fmt=None):
         if label_fmt is None:
             label_fmt = self.label_fmt
-        return [begin.strftime(label_fmt) for begin, end in self]
+        return [
+            begin.strftime(label_fmt.format(i=i, rev_i=len(self)-i))
+            for i, (begin, end) in enumerate(self)
+        ]
 
     def chunkify_qs(self, qs, field=None):
         if field is None: