Add realtime output from solver

Hey, great job with this ampl magic for ipython, found it super useful in debugging models/visualizing solutions quickly without having to parse a solution file or use AMPL shell.
I made a small (and ugly) change to get realtime output from the solver showing up inline, not only when the optimization is over, don't know if you like it.
By the way, there's an issue when stopping the execution in IPython notebook. 
In a (ipython) shell, Ctrl+C stops AMPL *and* solver, but in the notebook the solver is left hanging - and keeps eating CPU unless I kill it, or wait for the optimization to end.