* fix cv::imwrite to allow cv::UMat and vectors of it to be written

* cv::imwrite failure handling improvements

* Unit test for regression testing imwrite support for and fix whitespace

* added write as pbm

* add tests for pbm

* imgcodecs: PBM support

- drop additional PBM parameters
- write: fix P1/P4 mode (no maxval 255 value after width/height)
- write: invert values for P1/P4
- write: P1: compact ASCII mode (no spaces)
- simplify pbm test
- drop .pxm extension (http://netpbm.sourceforge.net/doc/ doesn't know such extension)

Implementation of bit-exact resize. Internal calls to linear resize updated to use bit-exact version. (#9468)

Drop code under *undefined* HAVE_TIFF
(violates several policies, like a way to turn off tiff support)

Previously, the return value of fwrite and fclose were not properly
checked, leading to possible silent truncation of the data if writing
failed, e.g. due to lack of disk space.

Fixes issue #9251.

autorotate in-memory jpegs (#8492)

* autorotate in-memory jpegs

* correct indentation (4 spaces)

* imgcodecs: don't apply EXIF rotation for unloaded images

* videoio: don't try to rotate MJPEG stream

* imgcodecs: ByteStreamBuffer::seekoff support all seek "dir"

* imgcodecs: fix condition: "off == egptr() - eback()" is valid offset

This patch implements the PAM image format as defined at:
http://netpbm.sourceforge.net/doc/pam.html

The PAM format provides a generic means for storing 2 dimensional information.
This is useful for opencv since there are cases where data gets translated into
non standardized formats, which makes it difficult to store and load this information.

The TiffDecoder keeps an open file handle.
As a consequence the file cannot be removed
before the TiffDecoder closes the file.

- renamed source files
- guard the contents - always include

by this new function we can set libjpeg "scale_denom" parameter and load jpeg images scaled 1/2 - 1/4 - 1/8
other image formats resized after loading

Jpeg2k color to greyscale conversion on non-Windows is done post decoding because system libjasper segfaults when decoding color images as greyscale.

(performance) Possible inefficient checking for 'lmap' emptiness
(warning) Assignment of function parameter has no effect outside the function. Did you forget dereferencing it?
(style) Array index '<xxx>' is used before limits check

1. someMatrix.data -> someMatrix.prt()
2. someMatrix.data + someMatrix.step * lineIndex -> someMatrix.ptr( lineIndex )
3. (SomeType*) someMatrix.data -> someMatrix.ptr<SomeType>()
4. someMatrix.data -> !someMatrix.empty() ( or !someMatrix.data -> someMatrix.empty() ) in logical expressions

Conflicts:
	modules/core/include/opencv2/core/cuda.hpp
	modules/cudacodec/src/thread.cpp
	modules/cudacodec/src/thread.hpp
	modules/superres/perf/perf_superres.cpp
	modules/superres/src/btv_l1_cuda.cpp
	modules/superres/src/optical_flow.cpp
	modules/videostab/src/global_motion.cpp
	modules/videostab/src/inpainting.cpp
	samples/cpp/stitching_detailed.cpp
	samples/cpp/videostab.cpp
	samples/gpu/stereo_multi.cpp