Add grammatrix(::KronPolynomial)#203

dlfivefifty wants to merge 3 commits intomasterJuliaApproximation/MultivariateOrthogonalPolynomials.jl:masterfrom

dl/krongrammatrixJuliaApproximation/MultivariateOrthogonalPolynomials.jl:dl/krongrammatrixCopy head branch name to clipboard