strings.tables: right-align cells if contents are starting with a digit

This should work great for the cells that contain numerical data. The patch
is submitted by @mrjbq7 in GitHub issue factor#1840.

README.md

@@ -70,6 +70,9 @@ are swapped compared to the original Factor implementation. I think my
 version makes the usage simpler, requiring less stack shuffling for typical
 usage, but the upstream developers decided they don't want to break
 compatibility by introducing this change;
+* a patch for strings.tables suggested by @mrjbq7 in issue
+[1840](https://github.com/factor/factor/issues/1840) is applied, so now the
+table cells containing numeric data are right-aligned;
 * other changes may be developed and contributed to upstream when ready,
 but the ones listed above represent either things not meant for general
 distribution or things already rejected.

basis/strings/tables/tables.factor

@@ -1,15 +1,20 @@
 ! Copyright (C) 2009, 2010 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel sequences fry math.order math.ranges splitting ;
+USING: ascii fry kernel math.order math.ranges sequences
+splitting ;
 IN: strings.tables
 
 <PRIVATE
 
 : format-row ( seq -- seq )
     dup longest length '[ _ "" pad-tail ] map! ;
 
+: pad-column ( str n -- str' )
+    CHAR: \s pick ?first [ digit? ] [ f ] if*
+    [ pad-head ] [ pad-tail ] if ;
+
 : format-column ( seq -- seq )
-    dup longest length '[ _ CHAR: \s pad-tail ] map! ;
+    dup longest length '[ _ pad-column ] map! ;
 
 PRIVATE>