once_cell 0.2.1

# Changelog

## 0.2.1

- implement `sync::OnceCell::get_or_try_init` if `parking_lot` feature is enabled
- switch internal `unsafe` implementation of `sync::OnceCell` from `Once` to `Mutex`
- `sync::OnceCell::get_or_init` is twice as fast if cell is already initialized
- implement `std::panic::RefUnwindSafe` and `std::panic::UnwindSafe` for `OnceCell`
- better document behavior around panics

## 0.2.0

- MSRV is now 1.31.1
- `Lazy::new` and `OnceCell::new` are now const-fns
- `unsync_lazy` and `sync_lazy` macros are removed

## 0.1.8

- update crossbeam-utils to 0.6
- enable bors-ng

## 0.1.7

- cells implement `PartialEq` and `From`
- MSRV is down to 1.24.1
- update `parking_lot` to `0.7.1`

## 0.1.6

- `unsync::OnceCell<T>` is `Clone` if `T` is `Clone`.

## 0.1.5

- No changelog until this point :(