Log Message:
Update graphics/opencv to 3.1.0.

* A lot of new functionality has been introduced during GSoC 2015:
  - "Omnidirectional Cameras Calibration and Stereo 3D Reconstruction"
    opencv_contrib/ccalib module
  - "Structure From Motion" - opencv_contrib/sfm module
  - "Improved Deformable Part-based Models" - opencv_contrib/dpm module
  - "Real-time Multi-object Tracking using Kernelized Correlation Filter"
    - opencv_contrib/tracking module
  - "Improved and expanded Scene Text Detection" - opencv_contrib/text
    module
  - "Stereo correspondence improvements" - opencv_contrib/stereo module
  - "Structured-Light System Calibration" - opencv_contrib/structured_light
  - "Chessboard+ArUco for camera calibration" - opencv_contrib/aruco
  - "Implementation of universal interface for deep neural network
    frameworks" - opencv_contrib/dnn module
  - "Recent advances in edge-aware filtering, improved SGBM stereo
    algorithm" - opencv/calib3d and opencv_contrib/ximgproc
  - "Improved ICF detector, waldboost implementation"
    - opencv_contrib/xobjdetect
  - "Multi-target TLD tracking" - opencv_contrib/tracking module
  - "3D pose estimation using CNNs" - opencv_contrib/cnn_3dobj

* Many great contributions made by the community, such as:
  - Support for HDF5 format
  - New/Improved optical flow algorithms
  - Multiple new image processing algorithms for filtering, segmentation
    and feature detection
  - Superpixel segmentation

* IPPICV is now based on IPP 9.0.1, which should make OpenCV even faster
  on modern Intel chips
* opencv_contrib modules can now be included into the opencv2.framework
  for iOS
* Newest operating systems are supported: Windows 10 and OSX 10.11
  (Visual Studio 2015 and XCode 7.1.1)
* Interoperability between T-API and OpenCL, OpenGL, DirectX and Video
  Acceleration API on Linux, as well as Android 5 camera.
* HAL (Hardware Acceleration Layer) module functionality has been moved
  into corresponding basic modules; the HAL replacement mechanism has
  been implemented along with the examples

See full changelog:

  https://github.com/Itseez/opencv/wiki/ChangeLog