Implementation of Clone, Debug and documentation for structures

[Mingun]

Resolves two cases from #19. I add only trivial implementations -- for example, for Drain implementing of Debug not trivial, so I do not add it

[cuviper]

These all look good to me, thanks!

AFAICS this doesn't affect the minimum supported rustc though, so let's make it 1.0.3 instead of bumping to 1.1. The policy documented in src/lib.rs is to keep consistent for any given 1.x series.

[bluss]

I don't mind bumping to 1.1 while keeping the same minimum Rust version. Since these are new features, 1.1 seems more correct.

[Mingun]

The policy documented in src/lib.rs is to keep consistent for any given 1.x series.

I tried to study attentively documentation on policy of bumping version and I did not find its any accurate mentioning. The quote from src/lib.rs very general therefore I tried to adhere to semver:

• major changes at incompatible changes
• minor changes when adding new functionality
• patch changes at a bugfix and changes which are not changing behavior

As from the point of view of the library user I should depend on major.minor version, but not on major.minor.patch version (otherwise I lose automatic receiving bugfixes), I changed minor version. Thus, depending on version 1.1 I will be able accurately to tell that in the project I need functionality, that this PR implements. If I changed patch, then the project depending on 1.0 (which it should depend) and using new opportunities from 1.0.3 could break if the real version would be 1.0.0-1.0.2.

[cuviper]

OK, I don't feel strongly about the version, if you're both happy with 1.1.

[Mingun]

ping

[cuviper]

I added Debug for IntoIter using vec::IntoIter::as_slice() to access the items. I think we could also do Drain and IterMut if vec::Drain and slice::IterMut exposed slices, which I'll propose in std. For now, this seems good enough.

Thanks!