added small toAA function

[UplinkCoder]

added small function to get an AA
(e.g. for serializeToJson)
does not handle extended fields though.

[UplinkCoder]

at a long term it would maybe pay to make the serializeTo functions DictionaryList-aware.
But I have no Idea how to go about that

[s-ludwig]

A few points to think about:

• A DictionaryList can contain multiple values per key
• Key may have different case, but are compared case insensitive
• The insertion order is preserved

These all make the AA conversion lossy, which would be an issue especially when using it for (de)serialization. I'm wondering what would be the best interface here, asAA, toAA or opCast(T)() if(is(T == Value[string])). I'm leaning towards opCast as the most idiomatic D - plus a cast also makes it a bit more obvious that there might be lost information.

For serialization, it would have to preserve all information, so it would have to be mapped to something like Tuple!(string, Value)[]. This could be achieved by implementing toJson/fromJson methods, but this wouldn't be really pretty here. Maybe the serialization framework should support defining a more generic serialized representation, independent of the output format. I'll open a separate issue for this.

BTW, would be nice to have the white space according to the style guide.

[UplinkCoder]

generic serialization is the way to go
closeing