by using the indices from the sorted distance vector of pairs.

In case of binary class, pred_m is initialized as zero vector and later
returned when raw outputs are requested, but it is never filled.

Fixed getSubset method to support Nx3 1-channel matrices as input (3xN 1-channel matrices doesn't supported at all).

Added test for checking that solvePnPRansac accepts vector<Point3f> and Nx3 1-channel or 1xN/Nx1 3-channel matrices as input.

Changed parameter order in documentation of findEssentialMat, because threshold and probability were switched.