Preserve ordered property when converting CategoricalPool

This was not visible before since the convert() method for arrays explicitly
called ordered!() even if it should not have been necessary.

Author: nalimilan

src/array.jl

@@ -275,7 +275,7 @@ for (A, V, M) in ((:CategoricalArray, :CategoricalVector, :CategoricalMatrix),
 
             refs = convert(Array{R, N}, A.refs)
             pool = convert(CategoricalPool{T, R}, A.pool)
-            ordered!($A(refs, pool), isordered(A))
+            $A(refs, pool)
         end
         convert{S, T, N, R}(::Type{$A{T, N}}, A::CatArray{S, N, R}) =
             convert($A{T, N, R}, A)

src/pool.jl

@@ -72,7 +72,7 @@ function Base.convert{S, R}(::Type{CategoricalPool{S, R}}, pool::CategoricalPool
     indexS = convert(Vector{S}, pool.index)
     invindexS = convert(Dict{S, R}, pool.invindex)
     order = convert(Vector{R}, pool.order)
-    return CategoricalPool(indexS, invindexS, order)
+    return CategoricalPool(indexS, invindexS, order, pool.ordered)
 end
 
 function Base.show{T, R}(io::IO, pool::CategoricalPool{T, R})

test/05_convert.jl

@@ -29,4 +29,8 @@ module TestConvert
     @test promote(1, v1) === (1, 1)
     @test promote(1.0, v1) === (1.0, 1.0)
     @test promote(0x1, v1) === (1, 1)
+
+    # Test that ordered property is preserved
+    pool = CategoricalPool([1, 2, 3], true)
+    @test convert(CategoricalPool{Float64, UInt8}, pool).ordered === true
 end