It took me a while to figure out what was meant with

    OpenCV Error: Assertion failed (i < 0) in getMat

While searching for this error message I found [a list of error
messages](https://adventuresandwhathaveyou.wordpress.com/2014/03/14/opencv-error-messages-suck/)
which also explained what the problem was: The data type for `rvecs` was
not a simple `cv::Mat` but a `std::vector<cv::Mat>`.

After I fixed that, I got the next error message:

    OpenCV Error: Assertion failed (ni > 0 && ni == ni1) in
    collectCalibrationData, file
    /build/buildd/opencv-2.4.9+dfsg/modules/calib3d/src/calibration.cpp,
    line 3193

The problem here was that my data type for the `objectPoints` was just
`vector<Vec3f>` and not `vector<vector<Vec3f>>`.

In order to save other people the time looking for this, I added
explicit examples of the needed data types into the documentation of the
function. I had to re-read the current version a couple of times until I
can read the needed levels of `vector<>`. Having this example would have
really helped me there.

Added a mention within calib3d.hpp that the flag RHO is available as an
option on calls to findHomography().

Implements the RHO algorithm as presented in

Paper: Bilaniuk, Olexa, Hamid Bazargani, and Robert Laganiere. "Fast
Target Recognition on Mobile Devices: Revisiting Gaussian Elimination
for the Estimation of Planar Homographies." In Computer Vision and
Pattern Recognition Workshops (CVPRW), 2014 IEEE Conference on, pp.
119-125. IEEE, 2014.

- Complete, heavily documented reference C implementation, as well as
temporarily disabled dirty SSE2 port.
- Enabled tests for RHO in test_homography; Currently these fail
presumably due to too-stringent accuracy requirements.
- Refinement and final refinement are not yet functional; Do not pass
their corresponding flags to RHO.

quickly corrected the previous refactoring of features2d: moved from set(SOME_PROP, val) to setSomeProp(val)

 -cv::findHomography added a parameter for RANSAC iterations
 -cv::findHomography added a parameter for RANSAC confidence

Added function decomposeHomographyMat. New files added are homography_decomp.cpp and test_homography_decomp.cpp.
Modified files calib3d.hpp and camera_calibration_and_3d_reconstruction.rst.

Conflicts:
	modules/core/include/opencv2/core/cuda.hpp
	modules/cudacodec/src/thread.cpp
	modules/cudacodec/src/thread.hpp
	modules/superres/perf/perf_superres.cpp
	modules/superres/src/btv_l1_cuda.cpp
	modules/superres/src/optical_flow.cpp
	modules/videostab/src/global_motion.cpp
	modules/videostab/src/inpainting.cpp
	samples/cpp/stitching_detailed.cpp
	samples/cpp/videostab.cpp
	samples/gpu/stereo_multi.cpp

Simle Java test for computeCorrespondEpilines added.