This change modifies destructors to anticipate that they can be called form a foreign thread if the GC is involved. The actual release of the reference will then happen deferred in the original thread.
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 The API is still mostly compatible with mainline vibe.d, but the driver systen has been replaced by the eventcore library and sockets/files/timers/...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.
