This allows subclasses of CvBoost to override initial weights that
update_weights uses without duplicating its entire implementation.

Backport from master.

http://code.opencv.org/issues/2926

OpenCV Manager verison incremeneted;
Docs and tests updated accordingly;
COnstant for Manager initialization added.

Native activity build warning fixed;
Logcat messages for JavaCameraView updated (Bug #2876);
Some fixes for feature #2893 done.

Based on pull request #685

Set ptr to NULL, so this method can be called repeatedly. This fixes a crash after unplugging web cam and trying to re-scan the cameras.

command line option '-Wsign-promo' is valid for C++/ObjC++ but not for C [enabled by default]

OpenCL StereoBeliefPropagation, ported from GPU implementation.

Add CL_CPU to supportsFeature check
simplify the logic of pyrlk