Add an extended continuum source (from a data cube) to the dither set
References __LEFTSPECTGR__, __RIGHTSPECTGR__, add_options(), SourceSimulator::AddContSource(), AddCosmics(), SourceSimulator::AddLineSource(), SourceSimulator::AddPoissonNoise(), SourceSimulator::AddSersicContSource(), SourceSimulator::AddSky(), DitherEnvironment::apply_atmospheric_extinction(), c, SourceSimulator::flambda_to_electrons(), g, VFrame::get_data(), DitherEnvironment::get_num_dithers(), DitherEnvironment::get_seeing(), DitherEnvironment::get_vframe(), DitherEnvironment::get_vframes(), DetectOptions::ifu_file, lin_interp(), SourceSimulator::log_fluxin(), SourceSimulator::mag_to_electrons(), norm_to_sdss_g(), prepend_filename(), print_usage(), DetectOptions::psf_size, MTRand::randPoisson(), DitherEnvironment::read_ditherfile(), DitherEnvironment::set_cmd_line(), DitherEnvironment::set_detect_parameters(), DitherEnvironment::setup_projectors(), sranddev(), DetectOptions::sub_cont, DitherEnvironment::version, version, and write_cmd_line().