Switched bitv to external iterators
Derive Clone for bitv stuff
Removed unecessary indirection in Bitv

BitvVariant is the same size as it was before (16 bytes).
Added iterator tests
Added bitv iterator benchmarks
Add slice_from and slice_to methods for vec, like the
methods of the same names that already exist for strs.
Minor cleanup of hashmap
Cleanup libsyntax a bit
std: add RtioTimer and UvTimer impl atop rt::uv
std: add rt::io::Timer
std: minor timer cleanup based on feedback
std: make check appeasement
auto merge of #7943 : Dretch/rust/vec-slice-from-to, r=huonw
extra: Remove uv, net, timer code

This will all be reimplemented in the new runtime.
extra: Add url module

Used to be under extra::net, which no longer exists
std: Remove weak_task API. Unused
std::rt: Stop using unstable::global in change_dir_locked
std: Move change_dir_locked to unstable. #7870
std: Remove unstable::global. Unused
std: Remove at_exit API. Unused