Outsource common code to implement concretize of lazy array operations

[schillic]

Compare:

LazySets.jl/src/LazyOperations/MinkowskiSumArray.jl

Lines 196 to 208 in 9fdf5e8

	function concretize(msa::MinkowskiSumArray)
	a = array(msa)
	@assert !isempty(a) "an empty Minkowski sum is not allowed"
	X = msa
	@inbounds for (i, Y) in enumerate(a)
	if i == 1
	X = concretize(Y)
	else
	X = minkowski_sum(X, concretize(Y))
	end
	end
	return X
	end

LazySets.jl/src/LazyOperations/CartesianProductArray.jl

Lines 658 to 670 in 9fdf5e8

	function concretize(cpa::CartesianProductArray)
	a = array(cpa)
	@assert !isempty(a) "an empty Cartesian product is not allowed"
	X = cpa
	@inbounds for (i, Y) in enumerate(a)
	if i == 1
	X = concretize(Y)
	else
	X = cartesian_product(X, concretize(Y))
	end
	end
	return X
	end