Added the copyrights missing in all files that required so.

Some interface was refined (most notably, the method for returning
Hessian was removed and the method for getting gradient was added as
optional to base Solver::Function class) and basic code for
setters/getters was added. Now is the time for the real work on an
algorithm.

In response to the pull request comments by Vadim Pisarevsky. In
particular, the following was done:
    *)cv::reduce use instead of custom code for calculating
per-coordinate sum
    *) naming style of private methods is made consisted with overall --
mixed-case style
    *) irrelevant create()'s were removed -- I did not know that copyTo()
method itself calls create

This caused warnings.

This is an implementation of so-called downhill simplex method
(https://en.wikipedia.org/wiki/Nelder%E2%80%93Mead_method)

Please, let me know if you have any comments, whoever you'd be.