- added new functions from core module: split, merge, add, sub, mul, div, ...
- added function replacement mechanism
- added example of HAL replacement library

removed optim module; moved its functionality to core and photo modules; moved drawing functions from core to imgproc. Removed FilterEngine etc. from public API

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.

HAVE_CONFIG_H -> HAVE_CVCONFIG_H