Remove non ascii characters for better compatibility.

pcigale/creation_modules/dl2014.py

@@ -48,9 +48,9 @@ class DL2014(CreationModule):
         )),
         ('alpha', (
             'float',
-            "Powerlaw slope dU/dM∝U¯ᵅ. Possible values are: 1.0, 1.1, 1.2, "
-            "1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, "
-            "2.6, 2.7, 2.8, 2.9, 3.0.",
+            "Powerlaw slope dU/dM propto U^alpha. Possible values are: 1.0, "
+            "1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, "
+            "2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0.",
             None
         )),
         ('gamma', (