Forget about the iterator type after constructing a JoinAll.

[dwrensha]

Fixes #285.

[dwrensha]

The current type parameter situation is left over from before #255, when JoinAll did in fact keep the iterator around as one of its fields.

[alexcrichton]

This seems reasonable to me, and it seems like we probably won't be storing the iterator in the JoinAll future any time soon as well, so seems fine moving forward. Could you add a test for this as well?

Unfortunately this is a breaking change so this can't land until 0.2, but I don't mind keeping this around until that time.

[dwrensha]

Test added.

[alexcrichton]

Awesome, thanks! I've tagged this to ensure it makes it into 0.2 and we don't forget about it.

[stuhood]

@alexcrichton : It looks like 0.2 might be ramping up. Would it be a good time to tackle this in order to help with #662?

[alexcrichton]

Certainly! I'd recommend coordinating with @cramertj though!

[cramertj]

@stuhood Thanks for your help! Can you send a PR to 0.2 in the next hour or so? If not, I'd recommend waiting until later this afternoon once I've had a chance to reorg 0.2 into multiple crates, otherwise the rebase will be a pain.

[stuhood]

@cramertj : Should be able to, as this PR is already green.

[cramertj]

@stuhood Great! ty :)

[stuhood]

@cramertj, @alexcrichton : Opened #732.

[alexcrichton]

Landed in #732