Ipython cell magic for venture

1. Get IPython 1.x (latest stable version).
2. Copy vent_magic.py to IPython profile startup directory. Try following at the terminal to get config: ipython locate config

   Then find the 'startup' folder. On my Ubuntu 1204 the full directory is:

     ~/.config/ipython/profile_default/startup
   

   If you now open a new IPython terminal, you should get this message:

   VentureMagics is active: see %vl? for docs

3. Basic examples can be found in the venture_magic_demo_vl.ipynb notebook or in the corresponding .html file. You can also use %vl? in the terminal.