A first pass at updating Tokio to use `std::future`.
Implementations of `Future` from the futures crate are updated to implement
`Future` from std. Implementations of `Stream` are moved to a feature flag.
This commits disables a number of crates that have not yet been updated.
Previously, every call to `current_thread::Handle::spawn` would go
through a `mpsc` channel. This is unnecessary when the `Handle` is still
on the same thread as the current thread executor. This patch fixes that
by storing the `ThreadId` of the executor when it is created, and then
comparing against that when `Handle::spawn` is called. If the call is
made from the same thread, `spawn_local` is used directly.
Fixes#562.
Extract `tokio::executor::current_thread` to a tokio-current-thread
crate. Deprecated fns stay in the old location. The new crate only
contains thee most recent API.
Carl Lerche