v0.1.1

• new feature: add whiten keyword argument to VBPP constructor with which the whitened representation of q(u) can be turned on.
• bugfix: add full_output_cov keyword argument to predict_f (though only False is implemented) so that the predict_f_samples method can be used
• docs: add note on matrix inversion issues (solution: fix inducing point locations).
• improved tests