Allow serializer/deserializer interface to use intermediate format instead of files

[rlux]

I want to serialize a property group to an intermediate ini object and manipulate it before writing it to a file. I want to deserialize a file to an ini object and manipulate it before parsing it as a property group.

Use case: I have several different types of proerty trees and want to encode in the ini file what type of tree it is. Currently this is only possible with a lot of warnings and a 2-pass parsing.

[mjendruk]

What about adding the possibility to serialize some meta information via Variants? That would be way easier.