Make json::to_xxx(&Json) fns Json::to_xxx(&self)

to_str, to_pretty_str, to_writer, and to_pretty_writer were at the top
level of extra::json, this moves them into an impl for Json to match
with what's been done for the rest of libextra and libstd.
Use the proper monomorphized ty::t for llvm alias hints. Closes #7260.
test: add support for sharding testsuite by passing --test-shard=a.b
Talk about trait bounds in the tutorial.
Document the task watching / exit code propagation implementation.
auto merge of #8719 : msullivan/rust/cleanup, r=catamorphism

r?
auto merge of #8722 : graydon/rust/2013-08-23-test-shard, r=msullivan

This makes it relatively easy for us to split testsuite load between machines in buildbot. I've added buildbot-side support for setting up builders with -a.b suffixes (eg. linux-64-opt-vg-0.5, linux-64-opt-vg-1.5, linux-64-opt-vg-2.5, linux-64-opt-vg-3.5, linux-64-opt-vg-4.5 causes the valgrind-supervised testsuite to split 5 ways across hosts).
auto merge of #8679 : singingboyo/rust/json-to-impl, r=alexcrichton

to_str, to_pretty_str, to_writer, and to_pretty_writer were at the top
level of extra::json, this moves them into an impl for Json to match
with what's been done for the rest of libextra and libstd.  (or at least for vec and str)

Also meant changing some tests.

Closes #8676.
auto merge of #8725 : bblum/rust/docs, r=graydon

This documents how to use trait bounds in a (hopefully) user-friendly way, in the containers tutorial, and also documents the task watching implementation for runtime developers in kill.rs.

r anybody
auto merge of #8732 : kballard/rust/str-truncate, r=thestinger
Force line ending of '.in' files in jemalloc to LF

This fixes issue #8731 . On Windows, if the git option core.autocrlf is true (github recommends users to turn on this flag - see https://help.github.com/articles/dealing-with-line-endings), the headers generated from the .in files will have syntatic errors, causing compilation to fail.
Merge pull request #8738 from mukilan/master

Force line ending of '.in' files in jemalloc to LF
Initial sketching out of the new path module
Implement GenericPath for PosixPath