I have another question concerning the following constraint from the wiki:

layered on top is a (more or less) 0.8.1 compatible high level API, using structs instead of classes to enable a scoped API without requiring all users to add scope to their request handlers

Which class needs to be changed?

I think that porting HTTPServerRequest and HTTPServerResponse to structs requires a change to the rest of the api, in particular the requestHandler provided by the user, to accept references to req and ref thus breaking the compatibility with the previous api.