Aiuti

Change Log:
- Added `batch_timeout` configuration for `AsyncBackgroundBatcher`
- Added handling for event loop shutdown in `AsyncBackgroundBatcher` to avoid log spam
- Improved thread-safety of `ensure_aw()` and `loop_in_thread()`

Change Log:
- Added the `AsyncBackgroundBatcher` class and `async_background_batcher()` decorator
- Dropped support for Python 3.6

Change Log:
- Fixed copyright notice in LICENSE

Change Log:
- Fixed `FileLock.acquire_ctx()` only releasing on error

Change Log:
- Updated all code to pass MyPy in strict mode
- Implemented a workaround for `BufferAsyncCalls.wait()` hanging on 3.7

Change Log:
- Added new asyncio functions: `ensure_aw()`, `loop_in_thread()`, and `run_aw_threadsafe()`
- Added `BufferAsyncCalls.wait_from_anywhere()` to support waiting for the buffer from potentially another thread
- Fixed potential deadlock in `to_sync_iter()` which could occur if the target event loop didn't continue to run