Revamp to reflection.

Changes in brief:
1. Descriptor is now the entry point for all reflection.
2. IReflectedMessage has gone; there's now a Descriptor property in IMessage, which is explicitly implemented (due to the static property).
3. FieldAccessorTable has gone away
4. IFieldAccessor and OneofFieldAccessor still exist; we *could* put the functionality straight into FieldDescriptor and OneofDescriptor... I'm unsure about that.
5. There's a temporary property MessageDescriptor.FieldAccessorsByFieldNumber to make the test changes small - we probably want this to go away
6. Discovery for delegates is now via attributes applied to properties and the Clear method of a oneof

I'm happy with 1-3.
4 I'm unsure about - feedback welcome.
5 will go away
6 I'm unsure about, both in design and implementation. Should we have a ProtobufMessageAttribute too? Should we find all the relevant attributes in MessageDescriptor and pass them down, to avoid an O(N^2) scenario?

Generated code changes coming in the next commit.

1 files changed, 2 insertions, 1 deletions

diff --git a/csharp/src/Google.Protobuf/Reflection/MapFieldAccessor.cs b/csharp/src/Google.Protobuf/Reflection/MapFieldAccessor.cs
index 317fbd8d..6df4c5f0 100644
--- a/csharp/src/Google.Protobuf/Reflection/MapFieldAccessor.cs
+++ b/csharp/src/Google.Protobuf/Reflection/MapFieldAccessor.cs
@@ -32,6 +32,7 @@
 
 using System;
 using System.Collections;
+using System.Reflection;
 
 namespace Google.Protobuf.Reflection
 {
@@ -40,7 +41,7 @@ namespace Google.Protobuf.Reflection
     /// </summary>
     internal sealed class MapFieldAccessor : FieldAccessorBase
     {
-        internal MapFieldAccessor(Type type, string propertyName, FieldDescriptor descriptor) : base(type, propertyName, descriptor)
+        internal MapFieldAccessor(PropertyInfo property, FieldDescriptor descriptor) : base(property, descriptor)
         {
         }