This makes arguments of type InputOutputArray required in python unless they
have a default value in C++.

As result following python functions changes signatures in non-trivial way:

* calcOpticalFlowFarneback
* calcOpticalFlowPyrLK
* calibrateCamera
* findContours
* findTransformECC
* floodFill
* kmeans
* PCACompute
* stereoCalibrate

And the following functions become return their modified inputs as a return
value:

* accumulate
* accumulateProduct
* accumulateSquare
* accumulateWeighted
* circle
* completeSymm
* cornerSubPix
* drawChessboardCorners
* drawContours
* drawDataMatrixCodes
* ellipse
* fillConvexPoly
* fillPoly
* filterSpeckles
* grabCut
* insertChannel
* line
* patchNaNs
* polylines
* randn
* randShuffle
* randu
* rectangle
* setIdentity
* updateMotionHistory
* validateDisparity
* watershed

e.g. <opencv2/core/core.hpp> become <opencv2/core.hpp>

Also renamed <opencv2/core/opengl_interop.hpp> to <opencv2/core/opengl.hpp>

Made all STL usages explicit to be able automatically find all usages of
particular class or function.

hopefully fixed handling of 'long' Python type in OpenCV bindings (bug #2193). added the corresponding test

Extended python bindings to support scalar values and tuples in place of InputArray (i.e. Mat) - ticket #2658. Added tests for #2611, #2505, #2658

Extended python bindings to support scalar values and tuples in place of InputArray (i.e. Mat) - ticket #2658. Added tests for #2611, #2505, #2658

changed diagnostic from "warning" to "note" in the python wrapper generator, to suppress some noise in opencv utilities

* always use "argN" names for unnamed arguments
* honor space symbol between typename and "*", "&" symbols
* fix indent errors

-Change input/output order from (out Labeled, in Image) -> (in Image, Out Labeled) and convert
to Input/OutputArrays in the process.

-Adopt OutputArray for statistics export so that the algorithm is "wrapper friendly" and not requiring a new struct in
language bindings at the expense of using doubles for everything and slowing statistics computation down..

[edit: cleaned whitespace]