aruco-python: There is no interface for custom board(3d) creation

[ShT3ch]

There only 2 methods:
CharucoBoard_create and GridBoard_create
Both of them create planar boards.

According to tutorials(http://docs.opencv.org/3.1.0/d9/d6d/tutorial_table_of_content_aruco.html#gsc.tab=0) it should be possible just pass my own objPoints(n x 4 x 3 matrices), ids(n-length integer vector) and markers dictionary. But reassigning fields of Board class from python isn't working. Also, there is no Board_create method.

I've tried to write Board::create by analogy from GridBoard::create.
There's my try:
To aruco.hpp I added to public of Board
CV_WRAP static Ptr<Board> create(InputArrayOfArrays objPoints, Ptr<Dictionary> &dictionary, InputArray ids);
And manually parsed InputArrayOfArrays and InputArray to vectors of vectors structures.
Here's the code. Looks ugly, but works from python.

I have no expirience in openCV module developing and even c++.
Is it written properly? Is it works? Should I add tests for it?

Should I create pull request with this implementation or somebody will write it in less ugly style?

[alalek]

#771 (#697)