Consistent naming of tutorials

doc/tutorials.rst

@@ -7,13 +7,13 @@ Tutorials
 
 All the tutorials are in tutorial directory. You can view them online too:
 
-- `Basic tutorial <http://nbviewer.ipython.org/urls/raw.github.com/iminuit/iminuit/master/tutorial/tutorial.ipynb>`_.
+- `Basic tutorial <http://nbviewer.ipython.org/urls/raw.github.com/iminuit/iminuit/master/tutorial/basic_tutorial.ipynb>`_.
   Covers the basics of using iminuit.
 - `Advanced tutorial <http://nbviewer.ipython.org/urls/raw.github.com/iminuit/iminuit/master/tutorial/advanced_tutorial.ipynb>`_.
   The advanced tutorial shows you how to speed up the computation of the
   objective function with Cython and how to write wrapper classes that work
   with iminuits parameter name discovery.
-- `Hard Core Cython tutorial <http://nbviewer.ipython.org/urls/raw.github.com/iminuit/iminuit/master/tutorial/hard-core-tutorial.ipynb>`_.
+- `Hard Core Cython tutorial <http://nbviewer.ipython.org/urls/raw.github.com/iminuit/iminuit/master/tutorial/hard_core_tutorial.ipynb>`_.
   If you need to do a huge likelihood fit that needs speed, this is for you.
   If you don't care, just use `probfit`_.
   It's a fun read though I think.