Add sample text search dictionary templates and parsers, to replace the

hard-to-maintain textual examples currently in the SGML docs.  From
Sergey Karpov.

contrib/dict_xsyn/sql/dict_xsyn.sql

@@ -0,0 +1,16 @@
+--
+-- first, define the datatype.  Turn off echoing so that expected file
+-- does not depend on contents of this file.
+--
+SET client_min_messages = warning;
+\set ECHO none
+\i dict_xsyn.sql
+\set ECHO all
+RESET client_min_messages;
+
+--configuration
+ALTER TEXT SEARCH DICTIONARY xsyn (RULES='xsyn_sample', KEEPORIG=false);
+
+--lexize
+SELECT ts_lexize('xsyn', 'supernova');
+SELECT ts_lexize('xsyn', 'grb');