0.2.0 Checklist

[Anders429]

This is the checklist of things that need to happen before the 0.2.0 release.

• Implement Iterator.
• Implement DoubleEndedIterator.
• Implement FusedIterator.
• Implement ExactSizeIterator. These must be dependent on the target's pointer width.
• Implement TrustedLen.
• Implement Index for [T], Vec<T>, &str, and String. Also implement Index for CStr using RangeFromExclusive.
• Implement Serialize and
  Deserialize from serde.
• autocfg is working towards some form of nightly feature probing. This needs to be available to make the above features usable, since some of them require nightly, but we don't want to restrict the crate to nightly.
• Set up documentation using doc_item to make it more clear what the requirements are for certain parts of the crate.
• rustdoc issue with foreign implementations not being shown in documentation needs to be resolved (see All Index implementations are not visible in documentation. #2). This only needs to be available in nightly, since that is what docs.rs uses. We need this to be fixed before release, or else half of the documentation will be missing. There is a PR to fix it, but it seems to be blocked currently.