Fixes for macosx 10.8

Changed -Wunused-private-field to -Wno-unused-private-field, now builds with Qt (iv)
Changed copy to copy_file to build with BOOST_FILESYSTEM_VERSION 3, in boost 1.46+

Need to leave for a couple of hours but if BOOST_FILESYSTEM_VERSION is defined as >= 3 for later versions of boost then boost::filesystem3 should be used and not boost::filesystem, right?