auto merge of #5863 : huonw/rust/rust-run-args, r=thestinger

e.g. 
```
$ cat echo.rs
fn main() {
   io::println(fmt!("%?", os::args()));
}
$ rust run echo.rs 1 2 3
~[~"./echo~", ~"1", ~"2", ~"3"]
```

src/librust/rust.rc

@@ -67,8 +67,8 @@ static commands: &'static [Command<'static>] = &[
  usage_line: "build an executable, and run it",
  usage_full: UsgStr(
  "The run command is an shortcut for the command line \n\
- \"rustc <filename> -o <filestem>~ && ./<filestem>~\".\
- \n\nUsage:\trust run <filename>"
+ \"rustc <filename> -o <filestem>~ && ./<filestem>~ [<arguments>...]\".\
+ \n\nUsage:\trust run <filename> [<arguments>...]"
  )
  },
  Command{
@@ -169,14 +169,14 @@ fn cmd_test(args: &[~str]) -> ValidUsage {
 
 fn cmd_run(args: &[~str]) -> ValidUsage {
  match args {
- [filename] => {
+ [filename, ..prog_args] => {
  let exec = Path(filename).filestem().unwrap() + "~";
  if run::run_program("rustc", [
  filename.to_owned(),
  ~"-o",
  exec.to_owned()
  ]) == 0 {
- run::run_program(~"./"+exec, []);
+ run::run_program(~"./"+exec, prog_args);
  }
  Valid
  }