Unbelipy

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- General Bugfixes
- Minor general improvements
- Documentation updates

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.. important::
This version causes breaking changes.

- Renamed all public methods to match the API's naming.
- ``UnbeliClient.get_leaderboard`` has been renamed to :meth:`UnbeliClient.get_guild_leaderboard`.
- ``UnbeliClient.get_balance`` has been renamed to :meth:`UnbeliClient.get_user_balance`.
- ``UnbeliClient.edit_balance`` has been renamed to :meth:`UnbeliClient.edit_user_balance`.
- ``UnbeliClient.set_balance`` has been renamed to :meth:`UnbeliClient.set_user_balance`.
- Allow users to input an open ``session`` keyword-argument in :class:`UnbeliClient`.
- Added :meth:`UnbeliClient.close` to allow users to close the current session when done using.
- Rename the names of some exceptions.
- ``ResponseError`` has been renamed to :exc:`HTTPException`.
- ``UnknownError`` has been renamed to :exc:`UnknownException`
- Removed ``roles`` and ``channels`` as a public attribute from :class:`Guild`.
- Fully setup documentation using Sphinx and readthedocs.io.

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- Bucket routes edited. Mainly user balance GET/PATCH/PUT and leaderboard.
- Fixed bug in :attr:`UnbeliClient.retry_rate_limits`.

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- Moved the rate limit throttler for buckets from the exit component of the context manager to enter, after acquiring the lock.

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- Rewritten rate limit handlers. :attr:`Client.rate_limits` now holds a ``buckets`` attribute, which is a dictionary containing the name of the bucket as key and its handler as the value.
- Bucket handlers are classes that hold specific bucket rate limit information updated with each request, and a context manager that throttles requests to prevent ``429``\s if that's enabled.
- ``True`` concurrency is only possible at the moment with different buckets.
- Dataclasses now contain an attribute "bucket" with the name of the bucket that produced the dataclass.
- This is useful to get the bucket handler from :attr:`UnbeliClient.rate_limits.buckets`.
- Next patch is expected to finally resolve rate_limit functionality.

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- Fixed bug with :meth:`ClientRateLimits.currently_limited` from :issue:`6`.