Added cudaGaugeField::exchangeExtendedGhost together with CUDA variant of ghost field extraction in extract_gauge_ghost_extended.cu.  Added new member GaugeField::ghostExchange to determine type of ghost zone storage and exchange used.
Addee FloatN order support for extended gauge copy.
Print out ghostExchange when printing GaugeParam structure.
FloatN order support in extended gauge field ghost extraction and GPU kernel bug fixes.
Reimplemented computeGaugeForceQuda using device-side extended ghost extraction and exchange.