Basic doxygen documentation support

- updated existing Doxyfile.in
- added corresponding cmake instructions
- added some specific files (layout, icon)
- clean existing doxygen warnings

Conflicts:
	CMakeLists.txt
	doc/CMakeLists.txt
	modules/core/include/opencv2/core.hpp
	modules/core/include/opencv2/core/base.hpp
	modules/core/include/opencv2/core/cuda.inl.hpp
	modules/core/include/opencv2/core/mat.hpp
	modules/core/include/opencv2/core/matx.hpp
	modules/core/include/opencv2/core/types.hpp
	modules/flann/include/opencv2/flann/lsh_table.h
	modules/imgproc/include/opencv2/imgproc.hpp
iOS framework build script changes

- buildbot process support (break build in case of errors)
- disabled some warnings in cmake script
Fixed iOS framework compilation warnings
iOS framework build script changes from master branch
superres: Fix return value VideoFrameSource_GPU

superres module fails to compile with the following error messages:

[100%] Building CXX object modules/superres/CMakeFiles/opencv_superres.dir/src/super_resolution.cpp.o
/opencv-2.4.10/modules/superres/src/frame_source.cpp: In function 'cv::Ptr<cv::superres::FrameSource> cv::superres::createFrameSource_Video_GPU(const string&)':
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:16: error: expected type-specifier before 'VideoFrameSource'
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:16: error: could not convert '(int*)operator new(4ul)' from 'int*' to 'cv::Ptr<cv::superres::FrameSource>'
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:16: error: expected ';' before 'VideoFrameSource'
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:41: error: 'VideoFrameSource' was not declared in this scope
/opencv-2.4.10/modules/superres/src/frame_source.cpp:264:1: error: control reaches end of non-void function [-Werror=return-type]
cc1plus: some warnings being treated as errors
make[3]: *** [modules/superres/CMakeFiles/opencv_superres.dir/src/frame_source.cpp.o] Error 1
make[3]: *** Waiting for unfinished jobs....

This is caused because the return value of the createFrameSource_Video_GPU function should be a VideoFrameSource_GPU object.
fixing SVM negative value rounding
Merge pull request #3364 from mshabunin:doxygen-docs-24
Merge pull request #3382 from StevenPuttemans:fix_3982
cmake/OpenCVGenPkgconfig.cmake: rework opencv.pc generation

Using absolute path to locate the components in the "Libs:" field of the
*.pc can badly break cross-compilation, especially when building
statically linked objects.

Indeed, pkg-config automatically replaces the '-I...' and '-L...' paths
when the PKG_CONFIG_SYSROOT_DIR and PKG_CONFIG_LIBDIR environment
variables are set [1]. This feature is very helpful and common in
cross-compilation framework like Buildroot [2,3].

When there are absolute paths in the *.pc files, pkg-config won't be
able to do the path substitions for these paths when the afromentioned
environment variables are set.
In such case, since the prefix is the target one, not the sysroot one,
these libraries' abolute paths will point to:
- in the best case: a non-existing file (i.e. these files do not exists
  on the host system;
- at worst: the host system's libraries. This will make the linking
  failed because these host system's libraries will most likely not be
  build for the target architecture [4].

So, this patch replace the components' absolute paths by the form:
  -L<libdir> -l<libname>

This way, the linker will be able to resolve each dependency path,
whatever the kind of objects/build (shared object or static build) it
is dealing with.

Note that for static link, the library order does matter [5]. The order
of the opencv components has been carefully chosen to comply with this
requirement.

Fixes #3931

[1] http://linux.die.net/man/1/pkg-config
[2] http://buildroot.org/
[3] http://git.buildroot.net/buildroot/tree/package/pkgconf/pkg-config.in
[4] http://autobuild.buildroot.net/results/e8a/e8a859276db34aff87ef181b0cce98916b0afc90/build-end.log
[5] http://stackoverflow.com/questions/45135/linker-order-gcc

Signed-off-by: Samuel Martin <s.martin49@gmail.com>

---
Note: this patch properly applies on top of the master branch, though it
      has been written on top of the 2.4 branch.
Merge pull request #3376 from vriera:2.4
Merge pull request #3294 from mshabunin:fix-ios-warnings-24
Merge pull request #3305 from tSed:opencv-2.4.x/opencv.pc-generation-refactoring