Add a property that allows to hide/display the selected item(s) in the r...

Add a property that allows the user to hide or display the selected item(s) in the result list. This functionality can be used for both single and multi select boxes. It was tested with inline options, data source, array data and tag array.

By default, the `hideSelectionFromResult` boolean property is `undefined` and leaves the expected behavior intact: the selected item from a single select box is visible inside the result list while the selected items from a multi select box are hidden from the result list. This default behavior can be overriden by setting the `hideSelectionFromResult` property to `true` or `false`.

Related issues: 
#1267 - Select a tag multiple times
#1538 - Ability to hide currently selected value in dropdown