Fix mpl = matplotlib import

Author: Enrique Fernandez

bag_tools/scripts/check_drop.py

@@ -39,7 +39,7 @@
 import matplotlib as mpl
 mpl.use('Agg')
 
-import mpl.pyplot as plt
+import matplotlib.pyplot as plt
 
 def check_drop(inbags, plot_format='png'):
   # Retrieve msg time, bag time and sequence number for all topics and messages:

bag_tools/scripts/plot.py

@@ -50,7 +50,7 @@
 import matplotlib as mpl
 mpl.use('Agg')
 
-import mpl.pyplot as plt
+import matplotlib.pyplot as plt
 
 
 def get_nested_attribute(msg, nested_attributes):