New yolov5 functionalities

• Methods for Yolov5 now is available (loadYoloModel, yoloOnFrame, closeYoloModel).
• Yolov5 and OCR model now is independent one to each other.

flutter_vision

A Flutter plugin for managing both Yolov5 model and Tesseract v4, accessing with TensorFlow Lite 2.x. Support object detection and OCR on both iOS and Android.