Support immutable output types in out-of-place scalar→vector gradient#212

ChrisRackauckas merged 1 commit intoJuliaDiff:masterJuliaDiff/FiniteDiff.jl:masterfrom

ChrisRackauckas-Claude:fix-immutable-gradient-scalar-inputChrisRackauckas-Claude/FiniteDiff.jl:fix-immutable-gradient-scalar-inputCopy head branch name to clipboard