Employee availability and unavailablity controls

Using the controls that appear over a day row (or a week row in Month view) it's now possible for employees to mark their availability or unavailability(where allowed) for all shifts listed on that day (or week) in a single click.

(Please note: Rotaville does not remember these clicks so if a rota manager subsequently adds a new shift then all availabilities for the new shift will initially be listed as unknown (ie. '?'))

Also, using use the keyboard commands, it's now possible to mark yourself as available (tick) or unavailable (x cross) for a single shift, whole day, or whole week. By marking out muliple rows in keyboard mode (J,K) it's possible to update multiple days or weeks with a single t or x key command.