Don't touch CRS on (de)serializing (#90)

Removes code that creates a default CRS on deserializing when JSON contains None, and that removes an existing default CRS when serializing.

According to https://tools.ietf.org/html/rfc7946#section-4, the CRS shouldn't be specified anyway, so it's not a good idea to create one whenever deserializing a CRS-less JSON object.

Author: supermihi

src/GeoJSON.Net.Tests/CoordinateReferenceSystem/DefaultCrsTests.cs

@@ -26,32 +26,8 @@ public void Can_Deserialize_When_Json_Does_Not_Contain_Crs_Property()
 
             var point = JsonConvert.DeserializeObject<Point>(json);
 
-            Assert.IsInstanceOf<DefaultCRS>(point.CRS);
+            Assert.IsNull(point.CRS);
         }
 
-        [Test]
-        public void Equals_GetHashCode_Contract()
-        {
-            var json = "{\"coordinates\":[90.65464646,53.2455662,200.4567],\"type\":\"Point\"}";
-
-            var point = JsonConvert.DeserializeObject<Point>(json);
-
-            var expected = DefaultCRS.Instance;
-            var actual = point.CRS;
-
-            Assert.AreEqual(expected, actual);
-
-            Assert.IsTrue(expected.Equals(actual));
-            Assert.IsTrue(actual.Equals(expected));
-
-            Assert.IsTrue(actual.Equals(actual));
-            Assert.IsTrue(expected.Equals(expected));
-
-            Assert.IsTrue(expected == actual);
-            Assert.IsTrue(actual == expected);
-
-            Assert.AreEqual(expected.GetHashCode(), actual.GetHashCode());
-
-        }
     }
 }

src/GeoJSON.Net/GeoJSONObject.cs

@@ -19,11 +19,6 @@ public abstract class GeoJSONObject : IGeoJSONObject, IEqualityComparer<GeoJSONO
     {
         internal static readonly DoubleTenDecimalPlaceComparer DoubleComparer = new DoubleTenDecimalPlaceComparer();
 
-        protected GeoJSONObject()
-        {
-            CRS = DefaultCRS.Instance;
-        }
-
         /// <summary>
         ///     Gets or sets the (optional)
         ///     <see cref="https://tools.ietf.org/html/rfc7946#section-5">Bounding Boxes</see>.
@@ -63,44 +58,6 @@ protected GeoJSONObject()
         [JsonConverter(typeof(StringEnumConverter))]
         public abstract GeoJSONObjectType Type { get; }
 
-        /// <summary>
-        ///     Called when [deserialized].
-        /// </summary>
-        /// <param name="streamingContext">The streaming context.</param>
-        [OnDeserialized]
-        private void OnDeserialized(StreamingContext streamingContext)
-        {
-            if (CRS == null)
-            {
-                CRS = DefaultCRS.Instance;
-            }
-        }
-
-        /// <summary>
-        ///     Called when [serialized].
-        /// </summary>
-        /// <param name="streamingContext">The streaming context.</param>
-        [OnSerialized]
-        private void OnSerialized(StreamingContext streamingContext)
-        {
-            if (CRS == null)
-            {
-                CRS = DefaultCRS.Instance;
-            }
-        }
-
-        /// <summary>
-        ///     Called when [serializing].
-        /// </summary>
-        /// <param name="streamingContext">The streaming context.</param>
-        [OnSerializing]
-        private void OnSerializing(StreamingContext streamingContext)
-        {
-            if (CRS is DefaultCRS)
-            {
-                CRS = null;
-            }
-        }
 
         #region IEqualityComparer, IEquatable