Add HoughTransform examples python2

houghlines.py for HoughLinesP() and HoughLines()
houghcircles.py for HoughCircles()
Merge pull request #779 from sivapvarma:master
ocl: Add dft based convolve implementation.

Match template in ocl module now can be utilized with dft based
convolve. Note this feature needs OpenCV to be built with clAmdFft
library.
Fix some compilation errors and warnings.
Add some documentation on ocl::convolve
fixed compilation with CUDA
fix build without gpu module with cuda
Merge pull request #784 from jet47:fix-gpu-build
Merge pull request #786 from cuda-geek:fix-build-gpu-off-cuda-on
Make rescaling flexible and add median filtering

Previously the pyramid was done with a rescaling factor of 2 (implied by the
use of pyrDown). This often leads to inferior results compared to a scale step
of e.g. 0.8 (a factor of 2 is obviously faster). This commit makes the scale
step configurable and uses a resonable default value.

The other change in this commit is that median filtering is added. This is not
described in this paper but it is done in the author's implementation. (See
e.g. "Secrets of optical flow estimation and their principles", Sun et al.,
CVPR 2010) This serves as periodic outlier removal during optimization, leading
to smoother flow fields while preserving motion edges. This includes splitting
the optimization loop into two loops.
updated GPU version of TVL1
fixed sanity test on Windows
Make imgproc.hpp independent from C API
Make highgui.hpp independent from C API
Make photo.hpp independent from C API
Make flann headers independent from OpenCV C API
Update documentation
Fix build errors
Merge pull request #724 from jet47:tvl1-updates
moved device layer to core module