Implement listbox control

[marco-sacchi]

Implement a listbox control to override game list management.

Provide the following features:

• scrolling of items by arrows, page up / down, home / end
• jump to a specific item by typing the first letters
• highlighting of occurrences in items of a specific string
• ability to hide items that do not match the string used for highlighting
• ability to view items on multiple columns (useful for rendering a list of files)

[marco-sacchi]

The following remain to be implemented:

• only display of the items that match the string for highlighting
• the arrangement on multiple columns

[marco-sacchi]

The items filtering is done into the class that handle programs list, so is not necessary. A clear method to empty the listbox it's enough.