Adding confirmation icons in Tachikoma's pull request, following considerations on security

icons.qrc

@@ -1,6 +1,11 @@
 <RCC>
   <qresource prefix="/" >
     <file>electrum.png</file>
+    <file>icons/clock1.png</file>
+    <file>icons/clock2.png</file>
+    <file>icons/clock3.png</file>
+    <file>icons/clock4.png</file>
+    <file>icons/clock5.png</file>
     <file>icons/confirmed.png</file>
     <file>icons/lock.png</file>
     <file>icons/preferences.png</file>

lib/gui_qt.py

@@ -410,7 +410,10 @@ class ElectrumWindow(QMainWindow):
             if tx['height']:
                 conf = self.wallet.blocks - tx['height'] + 1
                 time_str = datetime.datetime.fromtimestamp( tx['timestamp']).isoformat(' ')[:-3]
-                icon = QIcon(":icons/confirmed.png")
+                if conf < 6:
+                    icon = QIcon(":icons/clock%d.png"%conf)
+                else:
+                    icon = QIcon(":icons/confirmed.png")
             else:
                 conf = 0
                 time_str = 'pending'