Add support for serializing extension types

[agpreynolds]

Addresses #206

Add section to WriteComplexType method to add an xs:complexContent section to complex types with base types.

Tweak the method of property discovery - now only properties defined in a class are serialized to that class, inherited properties will be serialized via inheritance.

This means the following class structure and service definition:

[ServiceContract]
    public interface ITestService
    {
        [OperationContract]
        Cat GetCat();

        [OperationContract]
        Dog GetDog();
    }

public abstract class Animal
    {
        public Guid RequestId { get; set; }
        public Group Group { get; set; }
    }

    public class Cat : Animal
    {
        public string Name { get; set; }
    }

    public class Dog : Animal
    {
        public string Name { get; set; }
        public Breed Breed { get; set; }
    }

    public enum Breed { Terrier, Hound, Puppy }
    public enum Group { Mammal, Amphibian, Reptile }

Produces the following WSDL classes:

<xs:complexType xmlns:ser="http://schemas.microsoft.com/2003/10/Serialization/" name="Cat">
<xs:complexContent>
<xs:extension base="tns:Animal">
<xs:sequence>
<xs:element minOccurs="0" name="Name" nillable="true" type="xs:string"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="Cat" nillable="true" type="tns:Cat"/>
<xs:complexType xmlns:ser="http://schemas.microsoft.com/2003/10/Serialization/" name="Dog">
<xs:complexContent>
<xs:extension base="tns:Animal">
<xs:sequence>
<xs:element nillable="true" type="tns:Breed" name="Breed"/>
<xs:element minOccurs="0" name="Name" nillable="true" type="xs:string"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="Dog" nillable="true" type="tns:Dog"/>

Only bit i'm not happy with is the method of detecting a root class, type.BaseType.Name != "Object" seems a bit rubbish

[agpreynolds]

Hi, out of interest what type is being written that has a base type of null? I will add the null check and raise another PR

[psalmnoelff]

Hi guys, i was trying this feature out but it seems that its not being rendered as complex types in the xml/wsdl. Is there a config where I need to enabled this?