Fix bug in Scalar convert and add test (#219)

Author: kshyatt

src/Scalar.jl

@@ -10,7 +10,7 @@ const Scalar{T} = SArray{Tuple{},T,0,1}
 @inline Scalar(a::AbstractArray) = Scalar{typeof(a)}((a,))
 @inline Scalar(a::AbstractScalar) = Scalar{eltype(a)}((a[],)) # Do we want this to convert or wrap?
 @inline function convert(::Type{SA}, a::AbstractArray) where {SA <: Scalar}
-    return SA((a,))
+    return SA((a[],))
 end
 
 getindex(v::Scalar) = v.data[1]

test/Scalar.jl

@@ -5,4 +5,5 @@
     @test_throws ErrorException Scalar(2)[2]
     @test Scalar(2)[] == 2
     @test Tuple(Scalar(2)) == (2,)
+    @test Tuple(convert(Scalar{Float64}, [2.0])) == (2.0,)
 end