Switch the order of `pipes::stream`'s result

[brson]

stream returns (Chan, Port) but I intuitively expect (Port, Chan) (not sure why). I've seen others make this mistake too.

[nikomatsakis]

+1. Somehow "port and channel" sounds right, "channel and port" sounds
backwards.

[ben0x539]

The pipe syscall gives you the read end of the pipe first and the write end second, maybe that's why?

[BrendanEich]

@ben0x539 that's a good reason that Unix nerds like me find compelling, but I think @nikomatsakis is pointing to the poetic win of trochaic PORT and CHANnel vs. the awkwardly inverted foot in CHANnel and PORT.

/be

[catamorphism]

Done pending review (not that anything needs reviewing, but I wanted to make sure there was really consensus).

[catamorphism]

Done: 38bd694