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 a new tutorial "Using OpenCV Java with Eclipse". Removed information related to Eclipse from "Desktop Java" tutorial.
Attempt at fixing bug 3186
removed needless arithm_2_mat.cl file
marked some methods of ocl::Context as const
refactored and extended arithm operations add/sub/mul/div/absdiff
removed ocl::magnitudeSqr
removed comments from filtering.cpp and imgproc.cpp in ocl module
refactored and extended ocl::LUT
refactored and extended ocl::addWeighted
refactored and extended binary bitwise operations
refactored and extended ocl::compare
refactored and extended ocl::exp and ocl::log
refactoed and extended ocl::transpose
refactored arithm.cpp. Extended param list for all the tests
removed arithm_absdiff.cl
Merge pull request #1351 from barisdemiroz:eclipse-java-tutorial
Revert "cmake: fixed incorrect usage of add_definitions() on Linux"

This reverts commit 286244efedd215600b6be72d4c25e48af0ed1c2d.
Merge pull request #1199 from devernay:2.4-qtkit