Potential bug: Fix not to allow different types for template parameters

[fakedev9999]

IMO, as what I've suggested in this comment, #206 (comment).

template <typename Domain, typename Poly,
          typename Evals = typename Domain::Evals, typename F>
Evals CoeffToExtendedPart(const Domain* domain, const Poly& poly, const F& zeta,

this kind of code would be more correct to be written as below.

template <typename Domain>
typename Domain::Evals CoeffToExtendedPart(const Domain* domain, const typename Domain::Poly& poly, const typename Domain::Field& zeta,