* livescript is terse, but at least the numeric cast operator is a big plus
* expr-value casts to numeric (do we expect dates or types other than string and numeric here?)
* convert-question for type "range" casts min, max, step to numeric
* no extensive testing done yet with different ranges and constraints
* existing tests passing, no new tests added (coming next)
* tested: numeric question with appearance slider > XLSForm > Central > Collect works
* tested: numeric question with valid range > XLSForm > Central > Collect works

* Constraints work even if the values are strings
* Add tests for range parameters given as string getting converted to int