Common fixes:
- print function
- int / float division
- map, zip iterators in py3 but lists in py2

Known bugs with opencv 3.0.0
- digits.py, called via digits_video.py: https://github.com/Itseez/opencv/issues/4969
- gaussian_mix.py: https://github.com/Itseez/opencv/pull/4232
- video_v4l2.py: https://github.com/Itseez/opencv/pull/5474

Not working:
- letter_recog.py due to changed ml_StatModel.train() signature

Adding None as outImage in pos3 of cv2.drawKeypoints. Fixes bug that throws 'TypeError: Required argument 'outImage' (pos 3) not found' on left mouse button click

Reverted _doc.py to Python 2-only version. Interim measure to prevent docs from failing during build, until all samples are updated with Python 2/3 compatibility.

Prevent grabcut, houghcircles and houghlines python2 demos from running automatically while browsing demos in the demo list viewer

the service has been closed since 2013/2014

otherwise model is only ever trained with default
parameters, and digits_adjust does nothing (for example)

Conflicts:
	samples/CMakeLists.txt

fix whitespace

fixes for latest changes in opencv3.0 api

waitKey() normalization

fixed mser bindings

fixed find_obj.py

removed contrib, legacy and softcsscade modules; removed latentsvm and datamatrix detector from objdetect. removed haartraining and sft apps.
some of the stuff will be moved to opencv_contrib module.
in order to make this PR pass buildbot, please, comment off opencv_legacy, opencv_contrib and opencv_softcascade test runs.