refactor:

- update readme
- IMiddleware -> Middleware

refactor: rename things (#2)

* refactor: rename things

* minor: readme

Feat/coverage (#1)

* feat: coverage

* feat(readme): add coverage badge

feat(pyproject): add classifiers

minor: readme, pyproject tags

feat: add py.typed

refactor: add command, query, event dispatcher, observer interfaces

feat(dispatchers, observer): wrap handler with middlewares on register

minor(readme): update middleware example

hotfix: middlewares with multiply handlers

- problem: there were only one middleware instance, so available only one slot per handler.
- solution: use call_next as argument