FormHandler enhancements

FormHandler has two significant enhancements in Gramex 1.22.

Refresher: FormHandler lets you load data, filter it, and return in in different formats. It is asynchronous - so other requests will not be delayed while waiting for the database.

This release adds a modify: parameter. After the data is returned, you can modify or transform it in any way.

This release lets you create dynamic queries based on the URL query parameter. SELECT {by}, COUNT(*) GROUP BY {by} lets the user specify a ?by=city to group by city.

This release also lets you add default URL query parameters that you can modify using the prepare: parameter. This lets you modify the user inputs before running the filter.

With these changes, there should be NO REASON to use FunctionHandler to fetch data.