Problems with current IPC

These are notes on what could be changed in the current IPC model.

• Strings are encoded with uint for length then the full length of the string and then a NULL. The last NULL is a total waste of space.
• Most payload types are sent with a uint to identify the type first, except the below cases. This makes it hard to do generic getter methods.
  • error packets are encoded with the header and then directly the string, without the type.
  • dicts and propdicts are returned as a list with [key, value, key, value] layout, the same here, the type is set to dict or propdict and then the list comes as any other list but without the type field. it's a special case but it might be convenient to include the list type there also.
• In the return packet we don't really need object and cmd in the header, cookie and length should be enough. but to do this we need a better way to handle error packets.
• let's get rid of unsigned ints, just creates confusion.
• A dict is serialized different from a normal list or a propdict. The dict actually is serialized as string (key),type,value instead of the normal list or propdict that are serialized as type, key, type, value.
• Collection attributes appends a stringlist for the attributes, but the size of the list is sizeof(list)/2 because the serialization expects key/value pairs as size, not the number of entries in the list. this is not how the dict is serialized.