Reduce the size of the font for the error messages to make them fit in the slide.

doc/nextml2015/presentation.tex

@@ -643,6 +643,7 @@ f(np.ones((2,)), np.ones((3,)))
 \lstset{language=Python,
         commentstyle=\itshape\color{blue},
         stringstyle=\color{violet},
+        basicstyle=\scriptsize
         }
 \begin{lstlisting}
 Traceback (most recent call last):
@@ -668,6 +669,7 @@ Inputs scalar values: ['not scalar', 'not scalar', 'not scalar']
 \lstset{language=Python,
         commentstyle=\itshape\color{blue},
         stringstyle=\color{violet},
+        basicstyle=\footnotesize
         }
 \begin{lstlisting}
 HINT: Re-running with most Theano optimization