Ipython enhancements

this allows one to call isympy with either the --qt or --notebook flag and have isympy open up the corresponding ipython session type, with sympy already loaded (just like in the terminal), and with printing set up properly.

This only works with the latest testing IPython (1.0.dev), since it is new functionality, it is easy not to write to old APIs. It can always be backported to other IPython versions if 1.0 takes a while to reach a wide enough audience.

no existing functionality should be affected by this patch.