Make a mandelbrot set.    This example illustrates the resulting
speedup you can get by writing code in C.  To run the example,
first just try running the mandel.py program:

    % python mandel.py
    Wrote mandel.png
    12.3137500286 seconds
    %

Now, try making the LLVM extension module and running again:

    % make
    clang -emit-llvm -c _mandel.c
    % python mandel.py
    Wrote mandel.png
    0.817422151566 seconds
    %

Your timing numbers will vary of course.

