* Newton's method can be more efficient

when we get the result of function distortPoint with a point (0, 0) and then undistortPoint with  the result, we get the point not (0, 0). and then we discovered that the old method is not convergence sometimes. finally we have gotten the right values by Newton's method.

* modify by advice  Newton's method...#10574

* calib3d(fisheye): fix codestyle, update theta before exit EPS check

This reverts commit 5384a220.

Remove unnecessary Non-ASCII characters from source code (#9075)

* Remove unnecessary Non-ASCII characters from source code

Remove unnecessary Non-ASCII characters and replace them with ASCII
characters

* Remove dashes in the @param statement

Remove dashes and place single space in the @param statement to keep
coding style

* misc: more fixes for non-ASCII symbols

* misc: fix non-ASCII symbol in CMake file

The old error message was not giving any hint which input array (image)
led to an ill conditioned matrix. This made it near impossible to
identify poor images in a larger set.

A better approach would be to implement a checker function which gives
each image a rating before the real calibration is performed. This could
also include some image properties like sharpness, etc.

(2.4) Backports from master branch (#7854)

the current camera model is only valid up to 180° FOV for larger FOV the
undistort loop does not converge.
Clip values so we still get plausible results for super fisheye images >
180°.

Cast to (int) to avoid warnings

Add test for different points number case in fisheye calibration function

Fix for inconsistent asserts in cv::fisheye::initUndistortRectifyMap() which prevents from passing empty matrices in debug build (which is allowed according to the code bellow the asserts and the docs).

improves performance by factor 1.2 to 2.0

`A || !A` is `true` so write `(A && B) || !A` as `B || !A`