opt.add_option('--enable-debug', action='store_true', default = False, help = 'build with debugging information and without optimisation')
opt.add_option('--disable-gui', action='store_true', default = False, help = 'disable building of GUI tools')
opt.add_option('--target-windows', action='store_true', default = False, help = 'set up to do a cross-compile to Windows')
opt.add_option('--enable-debug', action='store_true', default = False, help = 'build with debugging information and without optimisation')
opt.add_option('--disable-gui', action='store_true', default = False, help = 'disable building of GUI tools')
opt.add_option('--target-windows', action='store_true', default = False, help = 'set up to do a cross-compile to Windows')