Develop QR detection module

[jgvictores]

Develop qrDetection2D module, similar to colorRegionDetection2D and haarDetection2D.

[PeterBowman]

In asrob-uc3m/robotDevastation, we adopted a well-established abandonware library, ZBar: ref, look for the ProcessorImageEventListener class. We also host the Windows 64-bit binaries: https://github.com/asrob-uc3m/ZBar.

[jgvictores]

Blocked by #79

[PeterBowman]

OpenCV 4.0 introduces QR code handling (ref, asrob-uc3m/robotDevastation#78 (comment)):

QR code detector and decoder have been added to opencv/objdetect module together with live sample. Currently, the decoder is built on top of QUirc library (which snapshot we put into opencv). Thanks to our intern Alexander Nesterov for this important contribution!

[jgvictores]

Unblocked, it should now be rather straightforward to implement this.

[PeterBowman]

I'm eager to work on this. Some research:

• OpenCV 4.0: first implementation (docs)
• OpenCV 4.3: adds support for multiple QRs on image (docs)
• OpenCV 4.5.1: adds support for curved QRs (docs, Detection and decoding of curved QR-codes opencv/opencv#18003)
• sample application: qrcode.cpp

QR code detection is built-in in OpenCV, whereas QR decoding is handled by the Quirc library embedded and conditionally built along with OpenCV (enabled by default).

[PeterBowman]

Done at e62cf53: C++ code + Python example + unit test. The new QRDetector device supports multiple QR codes in the supplied image if compiled with OpenCV 4.3+.

[PeterBowman]

OpenCV 4.5.2 (contrib) features the WeChat QR code detector based on CNN models.