Looks like we don't actually use them; when creating precompiled headers
with Visual C++, a dummy .cpp is created at build time.

disabled 64f IPP DFT; added IPP Gaussian filter; added IPP GetRectSubPix; added IPP BilateralFilter (temporarily disabled)

Example: img of size 10x10 and templ of size 11x9.
In subsequent code this will results in either width or height of
corrSize to be zero (0).
Line 261 will call crossCorr which will then have a zero size of either
blocksize.width or blocksize.height resulting in a division by zero
crach in lines 137 or 138.

Yes, it's as ludicrous as it sounds, but it's still true. Bizarrely,
the previous commit makes CLAHE run about 10% slower on Android, even
though it doesn't even touch any CLAHE code. Splitting it off fixes that,
although the reason it does is a mystery for the ages.

It's cleaner when it's in its own file, anyway. ;=]

This should allow many algorithms to take advantage of more parallelization
technologies.

Remove unused var "total"
Declare vars as locally as possible

issue #2678

On some platforms sin and cos are calculated in single precision resulting in
diversity of results.

Old implementation did

    lut[i] = 255 * (count(Y <= i)) / (width * height)

which actually shifts uniform histograms.
From now histogram is equalized as

    C = count(Y == min(Y))
    lut[i] = 255 * (count(Y <= i) - C) / (width * height - C)

disabled several tests on Mac when no FFMPEG is used; disabled automatic table initialization in imgwarp in the case of MinGW

Also removed assigned only variable.

[edit: cleaned whitespace]