Bug: Diet calculator never says “Never” on Save

If the calorie balance and desired weight change in the diet calculator page had different signs, the ``{\bf End date}'' in the form would display ``{\em Never}'' in the JavaScript code, but if the user pressed the ``Save'' button, it would inanely show an end date before the start date. I added code to the diet calculator form generation to preset the display modes of the ``{\bf End date}'' based on whether it is before or after the start date. Moving the mouse over a ``{\em Never}'' end date will open a date entry field---you still should be able to adjust the calorie balance to achieve a goal date even if the previous specification went in the wrong direction. (Reported by Robert Ewing.)