Newton constant and Mass of the Sun

Hi all,

This is not super important but I've just realised that the Newton constant and the Mass of the Sun have been added to the constants. In principle, we should never used these 2. The relative uncertainty on these 2 constants is of the order of 1E-4/1E-5 while the one on GM_Sun is of the order of 1E-12 and in practice, one always needs to evaluate GM and not G or M separately. So to avoid any mistakes, I would suggest to remove these 2 constants.