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?

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

Previously it was missing.
Ordered all descriptors by year of first publication.

Suggested by @SpecLad

* removed 2.0 PTX from default parameters since it has become obsolete
* added 3.5 BIN to prevent JIT compilation for super-Kepler