Add calculated fields where users can choose which prep types get included in the count

[tlammer]

Requested by Ohio Mollusks.

They would like to have more calculated fields either on the Collection Object form or in Statistics where they can say which prep types to include in the total.

Currently, on the CO form, there is a calculated count amount field that sums all prep types. They would like to be able to group some preparations together. For example, they want to know the count of items that involve shells. Three different prep types have shells involved, but 4 prep types do not. They would like to get a calculation of all items in those three preparations.