add a TotalOrd impl for the unit type
treemap: make set_advance public
treemap: indentation fixes
treemap: inline the TreeSet wrappers
treemap: add more tests for set difference
Add deriving_eq to Cell.
auto merge of #5318 : jdm/rust/deriving_cell, r=pcwalton

r? @pcwalton
core: Add vec::raw::mut_buf_as_slice
auto merge of #5305 : brson/rust/mut_buf_as_slice, r=brson

r?

Like `buf_as_slice` but for mutable pointers and slices.
rt/core: impl os::getcwd() in rust ref #4812
core: rt/core: impl os::env() in rust ref #4812
rt/core: port os::list_dir to rust ref #4812
core: change import of exchange_alloc for win32 os::_list_dir
core: fix broken tests on windows
core: formatting appeasement
core: link pthreads explicitly in linux build
core: convert asserts to fail_unless!
core: Convert obsolete fn syntax
auto merge of #5322 : brson/rust/4812, r=brson

Supersedes #5013
auto merge of #5292 : thestinger/rust/nil, r=graydon