opencv_core 1.3.1

OpenCV4 bindings for Flutter. This plugin does NOT include `highgui` and `videoio`, if you need them, please use `opencv_dart` instead.

1.3.1

• breaking change: hide highgui
• bump DartCvMacOS and DartCvIOS to 4.10.0.3, conditionally add link option -ld_classic

1.3.0

• bump dartcv to 0.0.3
• add cv.Mat.fromMat

0.0.2

• bump dartcv to 0.0.2

0.0.1

• initial release