Improve copy & deepcopy for MatSpaceElem

Also add a UndefInitializer constructor for it.

src/generic/GenericTypes.jl

@@ -1068,6 +1068,11 @@ struct MatSpaceElem{T <: NCRingElement} <: Mat{T}
     end
 end
 
+function MatSpaceElem{T}(R::NCRing, ::UndefInitializer, r::Int, c::Int)
+   t = Matrix{T}(undef, r, c)
+   return MatSpaceElem{T}(R, t)
+end
+
 function MatSpaceElem{T}(R::NCRing, A::AbstractMatrix{T}) where T <: NCRingElement
    return MatSpaceElem{T}(R, Matrix(A))
 end

src/generic/Matrix.jl

@@ -59,23 +59,11 @@ Base.isassigned(a::Union{Mat,MatRingElem}, i, j) = isassigned(a.entries, i, j)
 ################################################################################
 
 function copy(d::MatSpaceElem{T}) where T <: NCRingElement
-   z = similar(d)
-   for i = 1:nrows(d)
-      for j = 1:ncols(d)
-         z[i, j] = d[i, j]
-      end
-   end
-   return z
+   return MatSpaceElem{T}(base_ring(d), copy(d.entries))
 end
 
 function deepcopy_internal(d::MatSpaceElem{T}, dict::IdDict) where T <: NCRingElement
-   z = similar(d)
-   for i = 1:nrows(d)
-      for j = 1:ncols(d)
-         z[i, j] = deepcopy_internal(d[i, j], dict)
-      end
-   end
-   return z
+   return MatSpaceElem{T}(base_ring(d), deepcopy_internal(d.entries, dict))
 end
 
 function deepcopy_internal(d::MatSpaceView{T}, dict::IdDict) where T <: NCRingElement