Issue #5: added user option USE_BLACKMAGIC_DECKLINK_SDI_4K to main CMake file
Issue #5: added user option USE_BLACKMAGIC_DECKLINK_SDI_4K to main CMake file

gift-surg/GIFT-Grab,gift-surg/GIFT-Grab,gift-surg/GIFT-Grab,gift-surg/GIFT-Grab