Add Robin Thomas (author of the slice() comparability hack).
diff --git a/Misc/ACKS b/Misc/ACKS
index 5ac473d..ce2267f 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -375,6 +375,7 @@
 Christian Tanzer
 Amy Taylor
 Tobias Thelen
+Robin Thomas
 Eric Tiedemann
 Tracy Tims
 Jason Tishler