Merge pull request #120 from Thalmann/master

More user friendly error message

Author: fabianp

mprof

@@ -252,8 +252,9 @@ def add_brackets(xloc, yloc, xshift=0, color="r", label=None, options=None):
     """
     try:
         import pylab as pl
-    except ImportError:
+    except ImportError as e:
         print("matplotlib is needed for plotting.")
+        print(e)
         sys.exit(1)
     height_ratio = 20.
     vsize = (pl.ylim()[1] - pl.ylim()[0]) / height_ratio