Enable support for decimal literals in Turtle encoder

CHANGELOG.md

@@ -12,7 +12,8 @@ This project adheres to [Semantic Versioning](http://semver.org/) and
 - top-level alias functions for constructors of the basic datatypes
 - top-level constant functions `RDF.true` and `RDF.false` for the two boolean 
   RDF.Literal values
-- `RDF.Decimal` datatype for `xsd:decimal` literals
+- `RDF.Decimal` datatype for `xsd:decimal` literals and support for decimal 
+  literals in Turtle encoder
 - `RDF.Numeric` with a list of all numeric datatypes and shared functions for
   all numeric literals
 - the logical operators and the Effective Boolean Value (EBV) coercion algorithm 

lib/rdf/serializations/turtle_encoder.ex

@@ -13,7 +13,8 @@ defmodule RDF.Turtle.Encoder do
   @native_supported_datatypes [
     RDF.Datatype.NS.XSD.boolean,
     RDF.Datatype.NS.XSD.integer,
-    RDF.Datatype.NS.XSD.double
+    RDF.Datatype.NS.XSD.double,
+    RDF.Datatype.NS.XSD.decimal
   ]
   @rdf_type RDF.type
   @rdf_nil  RDF.nil

test/unit/turtle_encoder_test.exs

@@ -552,7 +552,6 @@ defmodule RDF.Turtle.EncoderTest do
          end)
     end
 
-    @tag skip: "TODO: Decimal literals"
     test "valid decimals" do
       [
         {1.0,       "1.0 ."},