Test fixes and rebase conflicts

* vec::raw::to_ptr is gone
* Pausible => Pausable
* Removing @
* Calling the main task "<main>"
* Removing unused imports
* Removing unused mut
* Bringing some libextra tests up to date
* Allowing compiletest to work at stage0
* Fixing the bootstrap-from-c rmake tests
* assert => rtassert in a few cases
* printing to stderr instead of stdout in fail!()

src/libstd/rt/task.rs

@@ -15,9 +15,10 @@
 
 use any::AnyOwnExt;
 use borrow;
+use cast;
 use cleanup;
 use io::Writer;
-use libc::{c_char, size_t};
+use iter::{Iterator, Take};
 use local_data;
 use ops::Drop;
 use option::{Option, Some, None};
@@ -488,7 +489,10 @@ mod test {
 
     #[test]
     #[should_fail]
-    fn test_begin_unwind() { begin_unwind("cause", file!(), line!()) }
+    fn test_begin_unwind() {
+        use rt::unwind::begin_unwind;
+        begin_unwind("cause", file!(), line!())
+    }
 
     // Task blocking tests