0.4.0-alpha.1

• Pin projection has become a safe operation.

• #[unsafe_project] has been replaced with #[pin_project].

• The Unpin argument has been removed - an Unpin impl is now generated by default.

• Drop impls must be specified with #[pinned_drop] instead of via a normal Drop impl.

• Unpin impls must be specified with an impl of UnsafeUnpin, instead of implementing the normal Unpin trait.

• Made #[project] attribute disabled by default.

See also tracking issue for 0.4 release.