NamedTuple switch broke add_default_options

[blegat]

The change in #1026 broke the following function:

Optim.jl/src/multivariate/optimize/interface.jl

Lines 21 to 27 in f43e608

	function add_default_opts!(opts::Dict{Symbol, Any}, method::AbstractOptimizer)
	for newopt in default_options(method)
	if !haskey(opts, newopt[1])
	opts[newopt[1]] = newopt[2]
	end
	end
	end

because iterating over a NamedTuple doesn't give pairs like a Dict.
This broke the tests for #929 (so if this PR had been merged, it would have detected the failure 😇 )

[pkofod]

Fixed, thank you .