Updates for OpenCV 3 api (keeping OpenCV 2 back compatibility)

Updates for OpenCV 3 api (keeping OpenCV 2 back compatibility).

Tested with:

• OpenCV 2.4.9
• OpenCV 3.1

(working with both 2 and 3 major versions).

Main changes:

• New paths for includes.
• Detectors/descriptors new api.

added 1 commit

• 973f1d99 - fix for test_roi_orb.cpp

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added 1 commit

• bdf32ae7 - Fix test_tracker_ORB.cpp

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added 1 commit

• 378a596b - Fix test_opencv.cpp

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added 1 commit

• e0c7d667 - new naming for OpenCV3 headers in OpenCV examples

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merged

mentioned in commit 14f5a7d7