introducing a tutorial for the retina model
adding retina tutorial
updated tutorial, need spell check, validation, nicer images and a discussion on parameters
updated tutorial, rapid spell check, retina parameters discussion added
added retina code tutorial
updated first image sample
minor update
minor updates for doc redirections and tutorial images size
added compute function to Feature2D (dirty workaround for #2699)
Front/back camera constants semantic for Android fixed (Bug #2839).

Front/Back camera constants' values changed;
Additional camera facing check added for JavaCameraView.
fix installation of main module headers

see: http://code.opencv.org/issues/2897

The order of the 2 conditions is really important, as every MATCHES
operator sets ${CMAKE_MATCH_1}, which is needed inside the condition
block. Ideally, this should be done using a single regex with a
negative forward lookahead, but CMake doesn't seem to support this
Merge ocl and/or/xor operators into one kernel each.
make boxfilter kernel compile on Mac GPU OCL
Add OclCascadeClassifierBuf interface
added an example of using cv::VideoCapture to read image sequences like 000.pmg, 001.png ... 100.png etc.
fixing build and lint warnings
Redo the Sphinx check to do the same thing on all platforms.

This also fixes the bug where the Sphinx version gets detected as
"Sphinx vX.Y.Z" instead of "X.Y.Z" on Unix-like systems.
Merge pull request #817 from pengx17:2.4_ocl_bitwise_cleanup
Merge pull request #829 from SpecLad:sphinx-ver-1
removed separate example for reading image sequences and modified starter_video.cpp to better explain the functionality of VideoCapture. I also added a bit more explanation in the documentation of the VideoCapture interface