acme: fix rounding in rows computation

R=rsc
CC=codebot
http://codereview.appspot.com/2007045
diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 21efdc2..544ba99 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -21,8 +21,9 @@
 Michael Teichgräber <mt4swm@googlemail.com>
 Michael Teichgräber <mt@ib.wmipf.de>
 Nikolai Saoukh <nikolai.saoukh@gmail.com>
+Rob Pike <robpike@gmail.com>
 Russ Cox <rsc@swtch.com>
 Tim Newsham <tim.newsham@gmail.com>
 Tony Lainson <t.lainson@gmail.com>
 Venkatesh Srinivas <extrudedaluminiu@gmail.com>
-grai <t.lainson@gmail.com>
+