Revert "Revert "Add rand_tangent for types (#172)""

This reverts commit 61a83ed.

Author: Miha Zgubic

src/rand_tangent.jl

@@ -57,3 +57,6 @@ function rand_tangent(rng::AbstractRNG, x::T) where {T}
         Tangent{T}(; NamedTuple{field_names}(tangents)...)
     end
 end
+
+rand_tangent(rng::AbstractRNG, ::Type) = NoTangent()
+rand_tangent(rng::AbstractRNG, ::Module) = NoTangent()

test/rand_tangent.jl

@@ -11,6 +11,15 @@ using FiniteDifferences: rand_tangent
         (:a, NoTangent),
         (true, NoTangent),
         (4, NoTangent),
+        (FiniteDifferences, NoTangent),  # Module object
+        # Types (not instances of type)
+        (Foo, NoTangent),  
+        (Union{Int, Foo}, NoTangent),
+        (Union{Int, Foo}, NoTangent),
+        (Vector, NoTangent),
+        (Vector{Float64}, NoTangent),
+        (Integer, NoTangent),
+        (Type{<:Real}, NoTangent),
 
         # Numbers.
         (5.0, Float64),