OpenCV pthreads-based implementation changes:
- rework worker threads pool, allow to execute job by the main thread too
- rework synchronization scheme (wait for job completion, threads 'pong' answer is not required)
- allow "active wait" (spin) by worker threads and by the main thread
- use _mm_pause() during active wait (support for Hyper-Threading technology)
- use sched_yield() to avoid preemption of still working other workers
- don't use getTickCount()
- optional builtin thread pool profiler (disabled by compilation flag)

Signed-off-by: Li Peng <peng.li@intel.com>

Signed-off-by: Li Peng <peng.li@intel.com>

* hogsvm compatibility with python3

* add HAL for FAST

* add new interface

* persistence: replace arbitrary limit of cn to 4 by CV_CN_MAX

* python: added persistence test, remove temp files

* fixup! python: added persistence test, remove temp files

* fixup! python: added persistence test, remove temp files

- reduce scope of i,k,j variables
- use cv::AutoBuffer
- template<bool onlyDistance> class KMeansDistanceComputer
- eliminate manual unrolling: CV_ENABLE_UNROLLED

- don't use RNG for "task size" parameters (N, K, dims)
- add "good" kmeans test data (without singularities: K > unique points)

* Bit-exact implementation of GaussianBlur smoothing

* Added universal intrinsics based implementation for bit-exact CV_8U GaussianBlur smoothing.

* Added parallel_for to evaluation of bit-exact GaussianBlur

* Added custom implementations for 3x3 and 5x5 bit-exact GaussianBlur

* Fix for QT image window rectangle

* Update window_QT.h

* Update window_QT.cpp

* trailing whitespace

* highgui: fix QT getWindowImageRect()

* cuda::cvtColor bug fix

Fixed bug in conversion formula between RGB space and LUV space.
Testing with opencv_test_cudaimgproc.exe, this commit reduces the number
of failed tests from 191 to 95. (96 more tests pass)

* Rename variables

cut one ocl kernel if normVariance is disabled,
also use native_powr for performance reason.
Signed-off-by: Li Peng <peng.li@intel.com>

Signed-off-by: Li Peng <peng.li@intel.com>