🚀 New
* Added a cache to the registers with default timeout 0.5 second.
* `Modbus.read_group()` calls `Modbus.get_all()` instead of reading individual registers sequentially. Since during a `status` all groups are read in quick succession, and with caching, this results in much faster status outputs.
✨ Improved
* Moved the logic to lock a connection while in use to `Modbus.connect()` and `disconnect()` from the context manager.
🔧 Fixed
* Use key `modbus` from configuration file to initialise a new `Modbus` instance when a configuration file path is passed.
* Fixed output of status flags with value zero.