Vzenith-client

Changed

- Rename class `Client` to `LicensePlateRecognizer`.

Fixed

- Invoke listener multiple times.
- Passing tuple as parameters to event listener.

Added

- `vzenith.client.Client`: method `cmd_ivsresult` to get IVS results.
- `vzenith.client.Client`: update `send_*` and `recv_*` methods to public.

Added

- Package `vzenith.packet` to represent communicating packets.
- Package `vzenith.client` to send command to Intelligent Video Systems.
- Package `vzenith.event` for event handling.