Read seconds as a double-float
Antik no longer rebinds *read-default-float-format*. If it is 'single-float, there could be some unexpected precision loss when parsing time intervals, so it is rebound to 'double-float for reading times. The seconds part of timeparse can now be a rational. If it's an integer, the time interval will be formatted as an integer for output. If it's a rational, the time interval will be coerced to a double float.