core::iter tests are all commented out

[brson]

this is no good

[catamorphism]

Huh, now there just aren't any tests!

[graydon]

much of this is tested in vec now, but not all; I will leave it open.

[graydon]

non-critical for 0.6, de-milestoning

[thestinger]

For some reason these are run-pass tests now. I've deprecated the old iter module and I'll make sure there are tests for all of the adaptors in the new one, so this can be closed.