This is the designated successor of the `vibe-d:core` sub package of [vibe.d 0.7.x](https://github.com/rejectedsoftware/vibe.d.git). The API is mostly compatible from a library user point of view, but the whole library has received some heavy lifting under the surface, close to a rewrite. Most classes have been replaced by reference counting structs and `@safe nothrow` attributes are now used throughout the library, whenever possible. Adding `@nogc` still has to be decided, because of its viral nature.
Another major design change is that instead of the previous driver model, there is now a separate, lower-level event loop abstraction ([eventcore](https://github.com/vibe-d/eventcore.git)) which follows a callback based Proactor pattern. The logic to schedule fibers based on events has been pulled out of this abstraction and is now maintained as a single function, leaving to a huge improvment in terms of robustness (most issues in the previous implementation have probably never surfaced in practice, but there turned out to be lots of hidden bugs).
