Support a "Last Prepared" column

[kalekundert]

I'm imagining that this would be an alternative to (or maybe a replacement for) the "Ready" column. Instead of simply indicating whether or not a reagent is available, this would additionally give the date when it was made. This is useful information, because it makes it easier to go back in my lab notebook and see what happened last time.

[kalekundert]

Alternatively, I could have "Date Prepared" and "Date Expired", to automatically signal that a reagent should be remade after a certain date. It would be better to have the user specify an expiration duration, though, since that wouldn't need to be updated each time the reagent is made. What would be a good name for such a column? Maybe "Shelf Life"?