(videoCalibration): speedup chessboard detection

What does this MR do?

• Add a scaling factor to the input to run the detection algorithm on a downscaled image.
• Const-overload ::cvIO::moveToCV.
• Add a new preference parameter to configure the scaling in ARCalibration.

How to test it?

⚠ It is advised to test this in Release mode.

• Launch ARCalibration
• Test the calibration activity
• Try setting the scale in the chessboard parameters
• Set to 1, 0.5 and 0.25 and notice the speed-up.

Some results

All measurements were done on my machine : Windows 10 Intel Core-i7 6700K, 32Gb RAM

For a full HD image (1920x1080):

Scale	Average detection time
1	60ms
0.5	18ms
0.25	8ms

Associated Issues/Merge Requests

• Issues

  • Fixes #352 (closed)

• Merge requests

  • depends on !236 (merged)