Kutana

- Fixed case mistake in CommandsRouter
- Added better API for backends
- Added example for background actions

Changes

- Dramatically changed API
- Fixed unknown memory leak
- Added routers for more efficient updates dispatching
- Added more adequate documentation
- Added test with 100% coverage
- Updated examples
- Updated Makefile
- Updated codestyle
- Changed shape of `RequestException`

- Fixed issue with uploading documents to telegram

- Added more examples
- Updated `upload_doc` method
- Updated README
- Updated documentation
- Updated CI scripts
- Updated setup
- Rebranded engine to library
- Updated tests