add value validation for all insert functions

[fisher-j]

I'm envisioning a modular system where argument names and values are supplied to a single function that checks the value for each if it has a corresponding value checking function and raises an appropriate exception or messagebox if a problem is found. Once it is set up it can be added to each of the inserter functions via decorator, or adding it as a call within the function.

It might be best to implement as a regular call, because inserter functions might do some pre-processing before creating an insert query.