Adding functionality to serialize maps and collections directly from Por...

...tableReader/Writer.
It is sort of a problem with c++. Only way for user to use that with c++, if user know which type to read before reading. User should always give the type to readObject when calling. This is same for map and collections. Like following:
reader.readObject<MyEmployee>("field");
reader.readMap<int , MyEmployee>("field");
Secondly, user can not put arbitrary types of data to same map or collection. 
If we will support it, it should be clearly documented in c++ client.