applets: make sure pyqtgraph imports qt5

artiq/applets/big_number.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3.5
 
-from quamash import QtWidgets
+from PyQt5 import QtWidgets
 
 from artiq.applets.simple import SimpleApplet
 

artiq/applets/plot_hist.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3.5
 
 import numpy as np
+import PyQt5  # make sure pyqtgraph imports Qt5
 import pyqtgraph
 
 from artiq.applets.simple import SimpleApplet

artiq/applets/plot_xy.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3.5
 
 import numpy as np
+import PyQt5  # make sure pyqtgraph imports Qt5
 import pyqtgraph
 
 from artiq.applets.simple import SimpleApplet

artiq/applets/plot_xy_hist.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3.5
 
 import numpy as np
-from quamash import QtWidgets
+from PyQt5 import QtWidgets
 import pyqtgraph
 
 from artiq.applets.simple import SimpleApplet