typo in kmeans doc

* avoid rounding errors

* imgproc: replace condition in matchTemplate

* Fix reading of black-and-white (thresholded) TIFF images

I recently updated my local OpenCV version to 3.4.3 and found out that
I could not read my TIFF images related to my project. After debugging I
found out that there has been some static analysis fixes made
that accidentally have broken reading those black-and-white TIFF images.

Commit hash in which reading of mentioned TIFF images has been broken:
cbb1e867

Basically the fix is to revert back to the same functionality that has been there before,
when black-and-white images are read bpp (bitspersample) is 1.
Without the case 1: this TiffDecoder::readHeader() function always return false.

* Added type and default error message

* Added stdexcept include

* Use CV_Error instead of throw std::runtime_error

* imgcodecs(test): add TIFF B/W decoding tests

* Update imgproc.hpp

* update color conversion codes

http://www.libpng.org/pub/png/libpng.html

* RGB2RGB initially rewritten

* NEON impl removed

* templated version added for ushort, float

* data copying allowed for RGB2RGB

* inplace processing fixed

* fields to local vars

* no zeroupper until it's fixed

* vx_cleanup() added back

Fix distortion figure in calib3d. Positive radial distortion corresponds to pincushion distortion and negative to barrel distortion. Add another figure that illustrates the influence of k1 in the distortion effect.