Check kifu files more carefully so that inproper files are skipped.

An error example that has been fixed:
/home/kaneko/bin/mk_rate:570:in `add': Never reached! (RuntimeError)
  from /home/kaneko/bin/mk_rate:612:in `grep'
  from /home/kaneko/bin/mk_rate:675:in `main'
  from /home/kaneko/bin/mk_rate:675:in `glob'
  from /home/kaneko/bin/mk_rate:675:in `main'
  from /home/kaneko/bin/mk_rate:739

diff --git a/mk_rate b/mk_rate
index 5c8dd04..a035783 100755 (executable)
--- a/mk_rate
+++ b/mk_rate
@@ -653,7 +653,8 @@ def grep(file)
     black_id, white_id = $1.split(":").map {|a| a.strip}
     black_id = identify_id(black_id)
     white_id = identify_id(white_id)
-    if black_id && white_id && (black_id != white_id)
+    if black_id && white_id && (black_id != white_id) &&
+       black_mark && white_mark
       add(black_mark, black_id, white_id, white_mark, time)
     end
   end