Single 7_segment objects can now have multiple digits.

This is deduced from the digit size compared to the overall size.
The decimal point is now suppressed if there are not enough pins.
Added 02531A and 02352A 3 digit displays.

tests/7_segments.scad

@@ -21,9 +21,11 @@ use <../utils/layout.scad>
 
 include <../vitamins/7_segments.scad>
 
+function digits(s) = 7_segment_digits(s) < 2 ? 2 : 1;
+
 module 7_segments()
-    layout([for(s = 7_segments) 7_segment_size(s).x * 2], 5) let(s = 7_segments[$i])
-        7_segment_digits(s, 2);
+    layout([for(s = 7_segments) 7_segment_size(s).x * digits(s)], 3) let(s = 7_segments[$i])
+        7_segment_digits(s, digits(s));
 
 if($preview)
     7_segments();