Small typo fix in the documentation.
It was written 'devie' instead of 'device' in: 'Switching active device can be done using cuda::setDevice() function'

At least this is how it's defined in core/types_c.h

Conflicts:
	modules/core/doc/intro.rst

put it into core documentation

- disabled doxygen tree
- enabled doxygen enum listing
- added imgproc reference to main page
- enabled BiB support
- chenged doxygen root page format

In this particular case t shadows transpose of the base class Matx:
types.hpp:1805:14: warning: declaration of ‘t’ shadows a member of
'this' [-Wshadow]

Changelog gcc 4.8: The option -Wshadow no longer warns if a declaration
shadows a function declaration.

This warning is problematic because it prevents the module
opencv_contrib/modules/ruby to pass the build process

Fixed the non-working code example for NAryMatIterator.
The documentation of NAryMatIterator in file:
modules/core/include/opencv2/core/core.hpp has a working example which
was used for these edits.

fixed dependency of stitching module on xfeatures2d module as optional
fixed the initModule_xfeatures2d function that was called in module stitching since it is in another namespace than the standard cv one.

removed optim module; moved its functionality to core and photo modules; moved drawing functions from core to imgproc. Removed FilterEngine etc. from public API

Porting the [PR 2970](https://github.com/Itseez/opencv/pull/2970) To the new InputOutputArray type

At least this is how it's defined in core/types_c.h

put the detection-based tracker back (to objdetect module), so that the Android face detection sample builds fine. The patch by Konstantin Matskevich that adds C++11 threads support has been merged in too. Also, fixed compile error in the doc builder.

I propose forEach method for cv::Mat and cv::Mat_.
This is solution for the overhead of MatIterator_<_Tp>.

I runs a test that micro opecode runs all over the pixel of cv::Mat_<cv::Point3_<uint8_t>>.
And this implementation 40% faster than the simple pointer, 80% faster than iterator.
With OpenMP, 70% faster than simple pointer, 95% faster than iterator (Core i7 920).

Above all, code is more readable.

My test code is here.
    https://gist.github.com/kazuki-ma/8285876

Thanks.