Esper

- Add a simple event system, for registering and dispatching events.
- Replace usage of the lru_cache module with internal cache.
- To help with type checking, esper has been converted to a package.

Maintenance release

Changes
-------
- Update documentation with notes about dataclass decorator usage.
- Add Python 3.9 to Continuous Integration testing.

Maintenance release

Changes
-------
- Add missing docstrings.
- Add additional typing definitions.

This release brings two new convenience methods: `World.has_components` and `World.try_components`. These function identically to their singular versions, but allow querying for an arbitrary number of Components. In addition, many type names were privatized to prevent namespace pollution when you import esper.

This release contains a few small but important improvements. Calls to super() are no longer necessary in your Processor subclasses, which should eliminate a fair amount of boilerplate. The README has also been updated with more usage examples - all methods should now have at least one example. And finally, wheels are now uploaded to PyPi. This should help with packaging systems that only support wheels. Addresses issue 38.

Finally, version 1.0! I'm pretty happy with the library, and want to give thanks to everyone who has contributed. Also, thanks to all the users who have given feedback.

Esper is now using simple lru_caching internally by default.
The cache is currently flushed when adding or deleting Entities or Components from the
World, but Component queries are much faster generally. This will likely be improved in a
Future version. In addition to caching, Esper now supports passing kwargs to Processors.
Continuous Integration testing is now being done for all currently supported Python versions, including 3.7.