[csharp] More skin API changes, ports of commits 8d0ffd0 and 829fcc4. See #841.

spine-csharp/src/Attachments/MeshAttachment.cs

@@ -164,8 +164,7 @@ namespace Spine {
 			copy.g = g;
 			copy.b = b;
 			copy.a = a;
-			copy.deformAttachment = deformAttachment;
-
+			
 			CopyTo(copy);
 			copy.regionUVs = new float[regionUVs.Length];
 			Array.Copy(regionUVs, 0, copy.regionUVs, 0, regionUVs.Length);

spine-csharp/src/Attachments/VertexAttachment.cs

@@ -150,6 +150,7 @@ namespace Spine {
 				attachment.vertices = null;
 			
 			attachment.worldVerticesLength = worldVerticesLength;
+			attachment.deformAttachment = deformAttachment;
 		}
 	}
 }

spine-csharp/src/Skin.cs

@@ -83,9 +83,10 @@ namespace Spine {
 
 			foreach (SkinEntry entry in skin.attachments.Keys) {
 				if (entry.Attachment is MeshAttachment)
-					SetAttachment(entry.SlotIndex, entry.Name, ((MeshAttachment)entry.Attachment).NewLinkedMesh());
+					SetAttachment(entry.SlotIndex, entry.Name,
+						entry.Attachment != null ? ((MeshAttachment)entry.Attachment).NewLinkedMesh() : null);
 				else
-					SetAttachment(entry.SlotIndex, entry.Name, entry.Attachment.Copy());
+					SetAttachment(entry.SlotIndex, entry.Name, entry.Attachment != null ? entry.Attachment.Copy() : null);
 			}
 		}