This simplifies the logic by separating thread local notifications from cross-thread notifications, as well as replacing lockless operations by a spin lock. The thread local variant of ManualEvent is now also separated into a LocalManualEvent type.
The library is able to support simple TCP servers in the current state. The API is still mostly compatible with mainline vibe.d, but the driver systen has been replaced by the eventcore library and sockets/files/timers/... are now structs with automatic reference counting instead of GC collected classes. The stream interfaces have been removed for now.
