e.g. <opencv2/core/core.hpp> become <opencv2/core.hpp>

Also renamed <opencv2/core/opengl_interop.hpp> to <opencv2/core/opengl.hpp>

Common part of all source files is extracted to special header

Java tests fixes are expected shortly

More granular build of Java API: it is now possible to build Java wrappers only for the subset of OpenCV modules

Added new tests written by Hussein Abdinoor; Added support for new classes in features2d and imgproc

* fixed manually ported classes;
* added vector<vector<Point>> support;
* changed argument types for 3 functions;
* finished tests for org.opencv.core.Core class.

Testing: 1178/4/576

Testing: 1130/0/585

Java API: new converters, findFundamentalMat/cornerSubPix/findHomography/solvePnP/solvePnPRansac and their tests are updated

- fixed return of complex types (Scalar, Point, etc)
- partial implementation of vector<> support (empty stubs for CPP-side converters)