Add Mac OS X 64bit Support to libvidcap

This job is pretty straightforward so please don't bid if you don't have the precise expertise to do this job, which is actually very simple and quick if you have the right skills. **Ultimate goal**: make libvidcap compile and work on 64 Bit Mac OS X (has to compile and work on Darwin 10.7.3 for pay). Hint: QTCapture classes in the place of the current QuickTime framework sequence grabber currently used by libvidcap. Has to work side-by-side with current QuickTime framework support of the lib. All directives, variables and autoconf stuff has to detect 64 bit and choose QTKit instead of QuickTime framework. Example by adding sapi_qtkit.c and a qtkit directory just like it's done with current QT 32bit framework.