Added Gnu Public Licence documentation. Began converting documentation strings to use CLOD instead of CLDoc. Implemented 'fading when unfocussed' behaviour. Now most windows partly fade out when the mouse is not over them. Exceptions include background-windows and modal-windows. This behaviour can be defined per window using the 'window-transparency-unfocussed' slot. Also fixed a bug with characters from background window 'bleeding through' when overlying window was < 100% opaque.