feat: 切换后端至PaddleOCR-NCNN，切换工程为CMake

1.项目后端整体迁移至PaddleOCR-NCNN算法，已通过基本的兼容性测试
2.工程改为使用CMake组织，后续为了更好地兼容第三方库，不再提供QMake工程
3.重整权利声明文件，重整代码工程，确保最小化侵权风险

Log: 切换后端至PaddleOCR-NCNN，切换工程为CMake
Change-Id: I4d5d2c5d37505a4a24b389b1a4c5d12f17bfa38c

3rdparty/opencv-4.5.4/samples/python/video_v4l2.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python
+
+'''
+VideoCapture sample showcasing  some features of the Video4Linux2 backend
+
+Sample shows how VideoCapture class can be used to control parameters
+of a webcam such as focus or framerate.
+Also the sample provides an example how to access raw images delivered
+by the hardware to get a grayscale image in a very efficient fashion.
+
+Keys:
+    ESC    - exit
+    g      - toggle optimized grayscale conversion
+
+'''
+
+# Python 2/3 compatibility
+from __future__ import print_function
+
+import numpy as np
+import cv2 as cv
+
+def main():
+
+    def decode_fourcc(v):
+        v = int(v)
+        return "".join([chr((v >> 8 * i) & 0xFF) for i in range(4)])
+
+    font = cv.FONT_HERSHEY_SIMPLEX
+    color = (0, 255, 0)
+
+    cap = cv.VideoCapture(0)
+    cap.set(cv.CAP_PROP_AUTOFOCUS, 0)  # Known bug: https://github.com/opencv/opencv/pull/5474
+
+    cv.namedWindow("Video")
+
+    convert_rgb = True
+    fps = int(cap.get(cv.CAP_PROP_FPS))
+    focus = int(min(cap.get(cv.CAP_PROP_FOCUS) * 100, 2**31-1))  # ceil focus to C_LONG as Python3 int can go to +inf
+
+    cv.createTrackbar("FPS", "Video", fps, 30, lambda v: cap.set(cv.CAP_PROP_FPS, v))
+    cv.createTrackbar("Focus", "Video", focus, 100, lambda v: cap.set(cv.CAP_PROP_FOCUS, v / 100))
+
+    while True:
+        _status, img = cap.read()
+
+        fourcc = decode_fourcc(cap.get(cv.CAP_PROP_FOURCC))
+
+        fps = cap.get(cv.CAP_PROP_FPS)
+
+        if not bool(cap.get(cv.CAP_PROP_CONVERT_RGB)):
+            if fourcc == "MJPG":
+                img = cv.imdecode(img, cv.IMREAD_GRAYSCALE)
+            elif fourcc == "YUYV":
+                img = cv.cvtColor(img, cv.COLOR_YUV2GRAY_YUYV)
+            else:
+                print("unsupported format")
+                break
+
+        cv.putText(img, "Mode: {}".format(fourcc), (15, 40), font, 1.0, color)
+        cv.putText(img, "FPS: {}".format(fps), (15, 80), font, 1.0, color)
+        cv.imshow("Video", img)
+
+        k = cv.waitKey(1)
+
+        if k == 27:
+            break
+        elif k == ord('g'):
+            convert_rgb = not convert_rgb
+            cap.set(cv.CAP_PROP_CONVERT_RGB, 1 if convert_rgb else 0)
+
+    print('Done')
+
+
+if __name__ == '__main__':
+    print(__doc__)
+    main()
+    cv.destroyAllWindows()