min_const_generics sintaxe in nalgebra, removing typenum dependency

[guissalustiano]

With new min_const_generics stabilize in rust 1.51 is possible think about use Matrix<3, 2> sintaxe instead of current Matrix<U3, U2>?

[sebcrozet]

Hi! This is being worked on in #820. This will probably be complete next week. Not however that the typenum dependency can't be completely removed yet because of some limitations of min_const_generics. However the users of nalgebra will almost never have to use typenum directly any more.