Function checkIfChecked

Checks if a checkbox is selected and checks it if.

Package: plugins\zenpage
Author: Malte Müller (acrylian), Stephen Billard (sbillard)
Located at zp-extensions/zenpage/zenpage-admin-functions.php

Parameters summary
`string`	`$field`	the array field of an item array to be checked (for example "permalink" or "comments on")