pgsql: Improve headeline generation.

Log Message:
-----------
Improve headeline generation. Now headline can contain
several fragments a-la Google.

Sushant Sinha <sushant354(at)gmail(dot)com>

Modified Files:
--------------
pgsql/doc/src/sgml:
textsearch.sgml (r1.45 -> r1.46)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/textsearch.sgml?r1=1.45&r2=1.46)
pgsql/src/backend/tsearch:
ts_parse.c (r1.8 -> r1.9)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/tsearch/ts_parse.c?r1=1.8&r2=1.9)
wparser_def.c (r1.16 -> r1.17)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/tsearch/wparser_def.c?r1=1.16&r2=1.17)
pgsql/src/include/tsearch:
ts_public.h (r1.10 -> r1.11)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/tsearch/ts_public.h?r1=1.10&r2=1.11)
pgsql/src/test/regress/expected:
tsearch.out (r1.14 -> r1.15)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/tsearch.out?r1=1.14&r2=1.15)
pgsql/src/test/regress/sql:
tsearch.sql (r1.9 -> r1.10)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/tsearch.sql?r1=1.9&r2=1.10)