Enhanced tab navigation

This feature has been introduced as a result of customer feedback on the usability of the tab navigation bar within a phonelet. Currently the user is required to press the appropriate mode key to move right to the next tab. This was found to be too restrictive for the following reasons:
 * The use of the mode key to move tabs is not intuitive.
 * It is only possible to cycle through a set of tabs in one direction.

The UI team reviewed this situation and evaluated a number of proposed solutions which were then tested using a population that represents the normal customer for the phone.

As a result the UI team determined that the following approach should be developed for screens which include a tab navigation bar.
 * The tab bar becomes an item that can be highlighted by scrolling upwards in the screen.
 * Tabs can be scrolled in either direction using the Left and Right arrow keys.