core: Remove pipes::spawn_service, spawn_service_recv

These are only used in test cases; pipes isn't the right place for them;
they are unnecessary.

Conflicts:
	src/libcore/rt/uv/mod.rs
core: Just reordering some code
core: Remove #[doc(hidden)] attributes and atomic wrapper functions from pipes

Neither are needed
core: Inline the protocol definitions of sendp and oneshot

I want to be able to see what is going on
core: Remove a stray #[doc(hidden)] attribute
core::comm: Remove functions in favor of methods

`send`, etc. are never used. I've left the functions for oneshot pipes
because by-value methods don't work.
core::pipes: Just reordering declarations
core::comm: Modernize constructors to use `new`
auto merge of #5921 : brson/rust/pipes, r=brson

This builds on #5909. I've been combing through the pipes code to understand it and started refactoring a bit.

* Removes pipes::spawn_* functions. These are not particularly useful since they deal with low-level pipes types.
* Inlines the protocol-compiled definitions of `oneshot` and `streamp`. These are the only two uses of the protocol compiler in core and I'm inlining them so I can understand what they are doing as I work on pipes. I may un-inline them in the future.
* Removes redundant functions from core::comm
* Change the constructors to use the `new` convention