Porting a raylib example to GNU Algol 68

[Jose E. Marchesi]

> Hi Mohammad.
>
> I just tried the demo.  It works like a charm :)
>
>>   int k_mouse_button_left = 0;
>>   Color k_raywhite = (SHORTEN SHORTEN -11 {245},
>>                       SHORTEN SHORTEN -11 {245},
>>                       SHORTEN SHORTEN -11 {245},
>>                       SHORTEN SHORTEN -1 {255}),
>>         k_gray = (SHORTEN SHORTEN -126 {130},
>>                   SHORTEN SHORTEN -126 {130},
>>                   SHORTEN SHORTEN -126 {130},
>>                   SHORTEN SHORTEN -1 {255}),
>>         k_blue = (SHORTEN SHORTEN 0,
>>                   SHORTEN SHORTEN 121,
>>                   SHORTEN SHORTEN -15 {241},
>>                   SHORTEN SHORTEN -1 {255}),
>>         k_red = (SHORTEN SHORTEN -26 {230},
>>                  SHORTEN SHORTEN 41,
>>                  SHORTEN SHORTEN 55,
>>                  SHORTEN SHORTEN -1 {255});
>
> It seems to me, we may want to introduce an extension to allow a radix
> 10 for bits denotations, so in this sort of situation we could do:
>
>     Color k_raywhite = (short short 10r245,
>                         short short 10r245,
>                         short short 10r245,
>                         short short 10r255)

Also, half-serious, I think it would be fun to get a bit lispy and
accept:

   short, shoort, shooort, ...
   long, loong, looong, loooong, ...

in int and bits denotations, so:

  Color k_raywhite = (shoort 10r245,
                      shoort 10r245,
                      shoort 10r245,
                      shoort 10r255)

and same for mode declarers:

  mode Color = struct (shoort bits r,g,b,a)