Cachetools

===================

- Add FIFO cache implementation.

- Add MRU cache implementation.

- Improve behavior of decorators in case of race conditions.

- Improve documentation regarding mutability of caches values and use
of key functions with decorators.

- Officially support Python 3.9.

===================

- Improve ``popitem()`` exception context handling.

- Replace ``float('inf')`` with ``math.inf``.

- Improve "envkey" documentation example.

===================

- Support ``user_function`` with ``cachetools.func`` decorators
(Python 3.8 compatibility).

- Support ``cache_parameters()`` with ``cachetools.func`` decorators
(Python 3.9 compatibility).

===================

- Require Python 3.5 or later.

===================

- Document how to use shared caches with ``cachedmethod``.

- Fix pickling/unpickling of cache keys

===================

- Fix Python 3.8 compatibility issue.

- Use ``time.monotonic`` as default timer if available.

- Improve documentation regarding thread safety.