Added a writeFormat() method to Algorithm which must be called by the
write() method of derived classes.

OpenCV with the refactored features2d compiles! contrib is broken for now; the tests are not tried yet

OpenCV with the refactored features2d compiles! contrib is broken for now; the tests are not tried yet

reject contours with zero area by using the "continue" statement to be in sync with the condition checking style used in the whole file

change to reject contours with moms.m00 = 0.0

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

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

Made all STL usages explicit to be able automatically find all usages of
particular class or function.

added read/write methods for SimpleBlobDetector and DenseFeatureDetector; added their creation to FeatureDetector::create method (#1290)

HAVE_CONFIG_H -> HAVE_CVCONFIG_H