2015

to allow our code to solve systems of ODEs, I changed it so it assumes now that y0 is a non-scalar numpy.ndarray and that f outputs a non-scalar numpy.ndarray.
abstracted the extrapolation code into a separate function (ex_method_serial) that takes the method on which the extrapolation is based as an argument.
made ex-Euler an instance of ex_method_serial
implemented ex-midpoint as another instance of ex_methode_serial
Changed and added tests in tests.py accordingly