Hooks for image processing development
(Hopefully) improved the puzzle board recognition algorithm.
More changes of puzzle board recognition
Merge branch 'ui'
Added a shortcut to OpenCV initialization for the second or later calls.

The way MainActivity initializes OpenCV is changed again.
The capture button is always enabled, and pressing it after declined
installing OpenCV Manager asks the same thing again.
Added some comments.
Merge branch 'master' into ui
Added title to "Download OpenCV" dialog.