allow using other array types in TwiceOrderDifferentiable finite differences

[longemen3000]

xref JuliaNLSolvers/Optim.jl#924

[amrods]

Is this as easy as changing Vector to AbstractVector and Matrix to AbstractMatrix in

NLSolversBase.jl/src/objective_types/twicedifferentiable.jl

Line 116 in 62d2199

function fg!(storage::Vector, x::Vector)

and

NLSolversBase.jl/src/objective_types/twicedifferentiable.jl

Line 121 in 62d2199

function h!(storage::Matrix, x::Vector)

? If so, I can make that PR. I am needing that relatively quickly.

[longemen3000]

Yes, it's only that. If you need it right know without waiting for a PR, you can write a junction yourself that does what the Twicedifferentiable.jl constructor do

[amrods]

I'll do that in my fork directly, but I won't make a PR. I don't want to usurp it from you. I am afraid of messing up my packages though. I suppose I can remove the "official" version and instead install my fork.