DOC: Change figure size to 8 x 4.5 inch

Before, the x labels were cut off.
Also, now it's compatible to 16:9!

Author: mgeier

sfs/array.py

@@ -5,7 +5,7 @@
 
     import sfs
     import matplotlib.pyplot as plt
-    plt.rcParams['figure.figsize'] = 8, 4  # inch
+    plt.rcParams['figure.figsize'] = 8, 4.5  # inch
     plt.rcParams['axes.grid'] = True
 
 .. autoclass:: ArrayData

sfs/mono/source.py

@@ -6,7 +6,7 @@
     import sfs
     import numpy as np
     import matplotlib.pyplot as plt
-    plt.rcParams['figure.figsize'] = 8, 4  # inch
+    plt.rcParams['figure.figsize'] = 8, 4.5  # inch
 
     x0 = 1.5, 1, 0
     f = 500  # Hz