utils/split-pieces (QfConvert): Construct an instance of the right class.

Of course, `QfConvert' is always the right class at the moment, but it's
the principle of the thing.

diff --git a/utils/split-pieces b/utils/split-pieces
index 1c79315..a98cca5 100755 (executable)
--- a/utils/split-pieces
+++ b/utils/split-pieces
@@ -45,7 +45,7 @@ class QfConvert (object):
     else:
       seq = map(int, arg.split(','))
     print ";; piece widths = %r" % seq
-    return QfConvert(p, seq)
+    return cls(p, seq)
   def hack(me, n):
     if 2*n >= me.p: n -= p
     nn = []