IPP_VERSION_MAJOR * 100 + IPP_VERSION_MINOR*10 + IPP_VERSION_UPDATE
to manage changes between updates more easily.

IPP_DISABLE_BLOCK was added to ease tracking of disabled IPP functions;

Minor changes to IPP implementations;

fixes #5074

Refer to the following issue for detail:
https://github.com/Itseez/opencv/issues/5145

some mandatory string keys like paths must not be empty. Add the special
default value `<none>` so the CommandLineParser can enforce this and
generate an according error message for us.

requesting a previously undeclared key is most likely an programming
error. e.g. a typo "--unused vs --unsued".
So throw in those cases.

Add an according failure testcase.

fix position of assert expected/actual parameter

`has()` only tests for an argument presence which is always true for
arguments with default values. Use `get<bool>()` to check the value
instead.

and not consider its value. treat arguments with a set default value as
present.

`A || !A` is `true` so write `(A && B) || !A` as `B || !A`

Migration have been done for these ffmpeg/libav changes:

2013-12-11 - 29c83d2 / b9fb59d,409a143 / 9431356,44967ab / d7b3ee9 - lavc 55.45.101 / 55.28.1 - avcodec.h
  av_frame_alloc(), av_frame_unref() and av_frame_free() now can and should be
  used instead of avcodec_alloc_frame(), avcodec_get_frame_defaults() and
  avcodec_free_frame() respectively. The latter three functions are deprecated.

2012-10-08 - ae77266 / 78071a1 - lavu 51.74.100 / 51.42.0 - pixfmt.h
  Rename PixelFormat to AVPixelFormat and all PIX_FMT_* to AV_PIX_FMT_*.
  To provide backwards compatibility, PixelFormat is now #defined as
  AVPixelFormat.
  Note that this can break user code that includes pixfmt.h and uses the
  'PixelFormat' identifier. Such code should either #undef PixelFormat
  or stop using the PixelFormat name.

Disables TLS copy constructor and operator, as they can lead to errors and reservation of too much keys in TLS storage;

gather method was added to TLS to gather data from all threads;

Fix a bug. When reading from a saved model, function decomposeCovs() will be called. And if covMatType is COV_MAT_DIAGONAL, covsEigenValues is computed using SVD and eigen values are sorted so that the order of eigen values is not preserved. This would lead to different result when calling function predict2. This issues is discussed here: http://stackoverflow.com/questions/23485982/got-different-empredict-results-after-emread-saved-model-in-opencv.