* Add flags for build js

* Add poi.json

* Rebase whitelist into JSON file

* Rework generator of white_list

* Fix small typos

* Transfer opencv_js.josn in opencv_js.config.py

* Edit OPENCV_JS_WHITELIST

* Write comment

* Add description

* Fix typos in desc

* flag's append deleeted

* Fix whitespace

* variable deleted

* fix comment on lines 229 and 235

* Use circular lut hustory buffer in computeGradient of HOG

* Initialize prefetch data outside main loop.  Avoid code duplication.

- OPENCV_TRACE_ITT_ENABLE

- move TLS & instrumentation code out of core/utility.hpp
- (*) TLSData lost .gather() method (to dispose thread data on thread termination)
- use TLSDataAccumulator for reliable collecting of thread data
- prefer using of .detachData() + .cleanupDetachedData() instead of .gather() method

(*) API is broken: replace TLSData => TLSDataAccumulator if gather required
(objects disposal on threads termination is not available in accumulator mode)

I think it would help to change all 3 of the the input file arguments to be "positional" for consistency with the other tutorials. This also simplifies the command line input to run this tutorial by reducing typing, and helpfully prints the "usage" info if any of the 3 required inputs are missing.

I'm new to OpenCV and working through the tutorials. I kept getting runtime errors with this one until I realized that the arguments weren't positional, and I was missing the "--input1", "--input2, "--input3" flags preceding the filenames. All of the previous tutorials had required filenames as positional arguments and didn't require this.

The original code would require each input to be specified like this:
./compareHist_Demo --input1 filename1 --input2 filename2 --input3 filename3 

But with this change, the above command is simplified to:
./compareHist_Demo  filename1 filename2 filename3

This avoids a confusing runtime error to make things simpler for newcomers like me :)

Fixing bug with comparison of v_int64x2 or v_uint64x2

* Casting v_uint64x2 to v_float64x2 and comparing does NOT work in all cases.  Rewrite using epi64 instructions - faster too.

* Fix bad merge.

* Fix equal comparsion for non-SSE4.1. Add test cases for v_int64x2 comparisons.

* Try to fix merge conflict.

* Only test v_int64x2 comparisons if CV_SIMD_64F

* Fix compiler warning.

The usage function states that the default for match_conf is
0.65 if the default SURF feature finder is used, and 0.3 for
orbs. Indeed, if --feature orbs is used, match_conf is set
to 0.3f. This is a NOP, because the real default is also set
to 0.3f. Change it to 0.65f when SURF is in play.