core: get rid of OPENCV_NOSTL definition

Fix typo in harris corner detection tutorial.

fixed problem in concat layer by disabling memory re-use in layers with multiple inputs

trying to fix the tests when Halide is used to run deep nets

another attempt to fix Halide tests

see if the Halide tests will pass with concat layer fusion turned off

trying to fix failures in halide tests; another try

one more experiment to make halide_concat & halide_enet tests pass

continue attempts to fix halide tests

moving on

uncomment parallel concat layer

seemingly fixed failures in Halide tests and re-enabled concat layer fusion; thanks to dkurt for the patch

AVX optimized implementation of haar migrated to separate file

NaN values handling issue

Fix typo: 'right direction' to 'y direction' in harris corner detector tutorial.

BufferPoolController has a non virtual protected destructor (which is legitimate)

However, Visual Studio sees this as a bug, if you enable more warnings, like below
```
add_compile_options(/W3)     # level 3 warnings
add_compile_options(/we4265) # warning about missing virtual destructors
```

This is a proposition in order to silence this warning.

See https://github.com/ivsgroup/boost_warnings_minimal_demo for a demo of the same problem
with boost/exception.hpp

 - use universal intrinsic for base
 - dispatch for float/double version using AVX
 - AVX2 optimization not done yet

This is VS2017 Preview. It makes sure the version is detected properly and the INSTALL target then correctly installs to x64/vc15 (the same as MSVC1910).