core::rt: Move uv idle tests to idle mod
core::rt: Add bindings for async uv handles
Add AtomicUint newtype
core: Add AtomicInt and cleanup
core::rt: Add RemoteCallback trait and uv implementation

This is used for signalling the event loop from other threads.
core::rt: Add SchedHandle type
core::rt: Scheduler takes a WorkQueue

This will be for implementing a work-sharing strategy
core::rt: Remove UvEventLoop::new_scheduler function
core::rt: Add a very basic multi-threaded scheduling test
core::rt: Add SleeperList

Just a simple place to stuff handles to sleeping schedulers.
core::rt: Add SleeperList to Scheduler
core::rt: Add run_in_mt_newsched_task test function
core::rt: Outline the full multithreaded scheduling algo. Implement sleeping
core::rt: Fix an infinite recursion bug
core::rt: Change the signature of context switching methods to avoid infinite recursion
Merge remote-tracking branch 'brson/io' into incoming

Conflicts:
	src/libstd/rt/sched.rs
core::rt: Add some notes about optimizations
core::rt: Begin recording scheduler metrics
core::rt: Fix two multithreading bugs and add a threadring test

This properly distributes the load now
core::rt: deny(unused_imports, unused_mut, unused_variable)