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

Author: bors

doc/tutorial-tasks.md

@@ -236,7 +236,7 @@ Instead we can use a `SharedChan`, a type that allows a single
 use core::comm::{stream, SharedChan};
 
 let (port, chan) = stream();
-let chan = SharedChan(chan);
+let chan = SharedChan::new(chan);
 
 for uint::range(0, 3) |init_val| {
     // Create a new channel handle to distribute to the child task

src/compiletest/procsrv.rs

@@ -73,7 +73,7 @@ pub fn run(lib_path: ~str,
 
 
     writeclose(pipe_in.out, input);
-    let p = comm::PortSet();
+    let p = comm::PortSet::new();
     let ch = p.chan();
     do task::spawn_sched(task::SingleThreaded) || {
         let errput = readclose(pipe_err.in);