Merge branch 'patch-1' of https://github.com/npbarnes/Interpolations.jl into npbarnes-patch-1

Author: mkitti

src/extrapolation/filled.jl

@@ -30,7 +30,7 @@ extrapolate(itp::AbstractInterpolation{T,N,IT}, fillvalue) where {T,N,IT} = Fill
 @inline function (etp::FilledExtrapolation{T,N})(x::Vararg{Number,N}) where {T,N}
     itp = parent(etp)
     coefs = coefficients(itp)
-    Tret = typeof(prod(x) * zero(eltype(coefs)))
+    Tret = promote_type(eltype(coefs), typeof.(x)...,T)
     if checkbounds(Bool, itp, x...)
         @inbounds itp(x...)
     else