make it easy to set icons as classes

[wkeese]

It would be convenient if Checkbox, RadioButton, Combobox, etc. let you specify CSS classes for the icons. For example, Checkbox could have properties:

checkedIconClass: "",
uncheckedIconClass: "",

and then an application could (for example) set checkedIconClass="fa-check" to use the Font Awesome font icons for the Checkbox checkmark. Likewise for the down arrow in the Combobox, or for the up/down navigation in a PageableList.