107: Add a dummy lifetime to Wrapper r=taiki-e a=taiki-e

If we know that `Self` doesn't implement `Unpin` and `Self` doesn't contain any
generics or lifetimes, we get an error `E0277`.

To avoid this, add a dummy lifetime to the `Wrapper`. This allows
`Wrapper<Self>` to always compile regardless of whether `Self`
implements `UnsafeUnpin`.

As the `Wrapper` implements `UnsafeUnpin` regardless of a lifetime, this
should not change the actual bounds of the `Unpin` implementation.

This allows workaround of #102 that "using `pin_project(UnsafeUnpin)`
and not providing a manual `UnsafeUnpin` implementation" to work.

Closes #102 

cc @Aaron1011 @ogoffart

Co-authored-by: Taiki Endo <te316e89@gmail.com>

109: Release 0.4.0 r=taiki-e a=taiki-e

cc #21

### Changes since the latest 0.3 release:

* **Pin projection has become a safe operation.** In the absence of other unsafe code that you write, it is impossible to cause undefined behavior. (#18)

* `#[unsafe_project]` attribute has been replaced with `#[pin_project]` attribute. (#18, #33)

* The `Unpin` argument has been removed - an `Unpin` impl is now generated by default. (#18)

* Drop impls must be specified with `#[pinned_drop]` instead of via a normal `Drop` impl. (#18, #33, #86)

* `Unpin` impls must be specified with an impl of `UnsafeUnpin`, instead of implementing the normal `Unpin` trait. (#18)

* `#[pin_project]` attribute now determines the visibility of the projection type/method is based on the original type. (#96)

* `#[pin_project]` can now be used for public type with private field types. (#53)

* `#[pin_project]` can now interoperate with `#[cfg()]`. (#77)

* Added `project_ref` method to `#[pin_project]` types. (#93)

* Added `#[project_ref]` attribute. (#93)

* Removed "project_attr" feature and always enable `#[project]` attribute. (#94)

* `#[project]` attribute can now be used for `impl` blocks. (#46)

* `#[project]` attribute can now be used for `use` statements. (#85)

* `#[project]` attribute now supports `match` expressions at the position of the initializer expression of `let` expressions. (#51)

### Changes since the 0.4.0-beta.1 release:

* Fixed an issue that caused an error when using `#[pin_project(UnsafeUnpin)]` and not providing a manual `UnsafeUnpin` implementation on a type with no generics or lifetime. (#107)


Co-authored-by: Taiki Endo <te316e89@gmail.com>

111: Add a dummy lifetime to UnpinStruct r=taiki-e a=taiki-e

Basically the same as #107.

This fixes #102 completely.

cc #108


Co-authored-by: Taiki Endo <te316e89@gmail.com>

111: Add a dummy lifetime to UnpinStruct r=taiki-e a=taiki-e

Basically the same as #107.

This fixes #102 completely.

cc #108


Co-authored-by: Taiki Endo <te316e89@gmail.com>