fixed building OpenCV with IPP 6.x (different DFT API); added Canny and rectangular morphology (based on Alex Kapustin patches)

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

ReST directive was used. Also fixed some other ReST directives that were
not correct and removed some warnings during buildbot checks.

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

- Used lunix style slashes - works on most systems
- Removed all trailing whitespaces

adding/tuning multiple run for perf tests failing due to big deviation (functions using TBB can work so)

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.

The orientation of convexHull's result is currently the opposite of what the
documentation would suggest:

>>> import cv2, numpy as np
>>> points = np.array([[0,0],[0,1],[1,0]], dtype=np.int32)
>>> cv2.convexHull(points, clockwise=False)
array([[[1, 0]],
       [[0, 1]],
       [[0, 0]]], dtype=int32)
>>> cv2.convexHull(points, clockwise=True)
array([[[0, 0]],
       [[0, 1]],
       [[1, 0]]], dtype=int32)

Changing the function itself is probably not a good idea at this point, so
this fixes the documentation by flipping the coordinate system.

I also removed the mention of the origin, since it's irrelevant for this
function.

Also cv::, cv::gpu:: and cv::ocl:: namespace prefixes can be safely omitted
inside CV_ENUM and CV_FLAGS