Reduce allocations in ConcreteEvalaution indexing (#554)

Author: jishnub

src/Operators/functionals/Evaluation.jl

@@ -81,7 +81,7 @@ _eval(f, x) = f(x)
 _eval(f, x::SpecialEvalPtType) = boundaryevalfn(x)(f)
 function getindex(D::ConcreteEvaluation,k::Integer)
     T = prectype(domainspace(D))
-    f = Fun(D.space, [zeros(T,k-1); one(T)])
+    f = D.space(k-1)
     df = differentiate(f,D.order)
     v = _eval(df, D.x)
     strictconvert(eltype(D), v)