Someone points out that the Solo text formatter would be a lot

better if it marked empty cells with something other than a space.
So here's a three-bit change to turn it into a dot :-)

[originally from svn r6261]

solo.c

@@ -2442,7 +2442,7 @@ static char *grid_text_format(int c, int r, digit *grid)
         for (x = 0; x < cr; x++) {
             int ch = grid[y * cr + x];
             if (ch == 0)
-                ch = ' ';
+                ch = '.';
             else if (ch <= 9)
                 ch = '0' + ch;
             else