Improve handling of apostrophes

Change-Id: Id442f4e958720f970baef63aee9b8710c258e13b
diff --git a/src/tokenizer.xfst b/src/tokenizer.xfst
index fb97c5c..8026c01 100644
--- a/src/tokenizer.xfst
+++ b/src/tokenizer.xfst
@@ -69,7 +69,7 @@
 
 define Char \[WS|NL|Punct|Apos]; ! |¨;
 
-define Word Char+ ([Apos|Asterisk] Char+)*;
+define Word Char+ ([Apos|Asterisk] Char+)* ([s|S] [%’|%`]);
 
 define Plusampersand @txt"txt/plusampersand.txt";
 define Word [Plusampersand | Word] (Dash [Plusampersand | Word])*;