new function to `delimitedData`

[takeTrace]

Version of protoc (protoc --version)

3.0

Version of ProtocolBuffers.framework

3.0.0

Description

I have notice there google/protoc for Object-C have add a function call - (NSData *)delimitedData, it's really fit my situation because I use socket send Data without OutputStream, so with - (NSData *)delimitedData I can get a Data that specify size, just write to socket, then our server can deserialize correct.

i hope here can support that function, it'll be very useful, just a advice.