Support 'min' and 'max' values in the <f:number> tag

The <f:number> tag should support the 'min' and 'max' properties that <input type="number"> supports.

This will provide a modicum of client-side validation for constrained number fields, and limit the stepper buttons in the configuration UI, giving the user a stronger hint about the range of acceptable values.

Example:

<f:entry field="foo">
  <f:number min="10" max="100" />
</f:entry>

Will be rendered into an input tag like:

<input type="number" ...other properties... min="10" max="100">