core: Make atomic methods public
std::rt: Use AtomicUint instead of intrinsics in comm
std::rt: Destroy the task start closure while in task context
std::rt: Remove in incorrect assert
core::rt: Implement SharedChan
core::rt: Add SharedPort
core::rt: Add `MegaPipe`, an unbounded, multiple producer/consumer, lock-free queue
std: Fix stage0 build

Conflicts:
	src/libstd/rt/comm.rs
rt: Add rust_get_num_cpus
std::rt: Configure test threads with RUST_TEST_THREADS. Default is ncores x2
std::rt: Fix stream test to be parallel
std::rt: Fix a race in the UvRemoteCallback dtor
debugged a compiler ICE when merging local::borrow changes into the main io branch and modified the incoming new file lang.rs to be api-compatible