Flywheel

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* Constrain version of ``dynamo3`` dependency to avoid breakage

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* Bug fix: Fix refresh when using custom-typed primary keys (:pr:`63`)

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* Bug fix: Change limit behavior to match docs. ``query().limit()`` will limit the number of results, ``query().scan_limit()`` will limit number of items scanned (:issue:`57`)

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* Feature: Add ``update_schema()`` method to Engine (:pr:`53`)

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* **Breakage**: Removing support for overflow fields. The only fields flywheel will care about now are those that are explicitly set as a Field()
* Flywheel no longer forces raise_on_conflict to be True when you sync changes to fields that are part of a composite field. It is now up to the user to avoid putting their composite fields into an inconsistent state.
* Feature: sync() has a new argument, ``no_read``, which changes the behavior for syncing models with no changes. Instead of performing a GET, it will leave them as-is. This should make it easer to perform batch syncs without worrying as much about wasted bandwidth on GETs.
* ``Field`` has renamed the ``data_type`` argument to ``type`` (``data_type`` will still work)

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* Bug fix: Boolean overflow fields no longer decoded as decimals (:pr:`46`)