fast_atof: If a literal ends with a trailing dot (.), only parse further if the next character is a digit. In cases where the dot ends the literal (i.e. "1.") this would cause strtoul10_64 to throw an exception. To preserve as much of the old behaviour, we still consume trailing dots though. This "regression" was introduced (exposed) by #261, which added the extra check to strtoul10_64 that triggered here. This commit now fixes #304 (IFC file reading broken due to IFC files containing "(1.,1.,1.)" lists.