Use identity matrix if homography finding failed. Current behavior zeros out all points.

Update circlesgrid.cpp

Addressed comments

Update circlesgrid.cpp

removed whitespace

All of these: (performance) Prefer prefix ++/-- operators for non-primitive types.
[modules/calib3d/src/fundam.cpp:1049] -> [modules/calib3d/src/fundam.cpp:1049]: (style) Same expression on both sides of '&&'.

findHomagraphy can return empty Mat in master branch

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

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

rewritten several functions from calib3d: findhomography, findfundamentalmat, findessentialmat, estimateaffine3d, computecorrespondepilines, convert points{to/from}homogeneous to C++.

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

added COVAR_ and SORT_ enums to core.hpp; fixed many, many VS2005, VS2010 and MinGW (GCC 4.5.2) warnings

a big patch; use special proxy types (Input/OutputArray, Input/OutputArrayOfArrays) for passing in vectors, matrices etc.