fix cap_qtkit.mm for multithreaded applications

cap_qtkit does not work when the capture is run outside of the main
thread.
If the capture is launched in a separate thread, then [NSRunLoop
currentRunLoop] is not the same as in the main thread, and has no timer.
see
https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/F
oundation/Classes/nsrunloop_Class/Reference/Reference.html
"If no input sources or timers are attached to the run loop, this
method exits immediately"

Using usleep() (which I previously proposed, and was reverted) is not a
good alternative, because it may block the GUI.

Here is the new proposed solution:
- create a dummy timer so that runUntilDate does not exit immediately
- simplify the loop by using runUntilDate instead of runMode:beforeDate
- fix potential memory leaks (pointed out by Xcode's static analysis)
- fix init to follow Objective-C guidelines
- fax warnings about conversions from size_t to int
fix signedness error

OpenCV's automatic builds don't care if you store an unsigned int into
an int, but they don't want you to compare signed with unsigned. Does
that make sense?
Added bugfix #2795
- changing license header
- fixed bug in QtKit when changing camera resolution
Fix ocl compilation error when using Intel OpenCL SDK.
Add IPP support in cvtColor function
increase epsilon for GEMM & Convolve sanity tests for CUDA 5.5
Fix building the iOS framework after I dropped the VERSION macro.

This version uses CMake to generate Info.plist, which should be more
reliable than the old approach.
Fix a bug of retinaParameters.
When colorMode is set to 0 via Retina::_init method, _retinaParameters's
colorMode variable is not correctly assigned.
Minor language corrections in the tutorial document
Let ocl::filter2D support kernel size >= 3.
enabling of VideoCapture(String) [fixing issue #3207]
- enable auto-wrap of VideoCapture;
- minor refactoring of generated code templates.
also fixing JNI library name in JUnit tests
LinkedList -> ArrayList
Missing including of nonfree module to support the use of SURF
detector/descriptor.
CLAHE Python bindings
Update with apavlenko's suggestions.
Merge pull request #1245 from rdm12:doc_tutorial_camera_calibration
Merge pull request #1262 from StevenPuttemans:fix_surf_tutorial
Merge pull request #1263 from abidrahmank:pyCLAHE_24
Merge pull request #3 from Itseez/2.4

OpenCV changes