pgsql: Rename built-in Snowball stemmer dictionaries to be english_stem,

Log Message:
-----------
Rename built-in Snowball stemmer dictionaries to be english_stem,
russian_stem, etc.  Per discussion.

Modified Files:
--------------
    pgsql/src/backend/snowball:
        Makefile (r1.1 -> r1.2)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/snowball/Makefile?r1=1.1&r2=1.2)
        snowball.sql.in (r1.2 -> r1.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/snowball/snowball.sql.in?r1=1.2&r2=1.3)
    pgsql/src/include/catalog:
        catversion.h (r1.417 -> r1.418)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.417&r2=1.418)
    pgsql/src/test/regress/expected:
        tsearch.out (r1.2 -> r1.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/tsearch.out?r1=1.2&r2=1.3)
    pgsql/src/test/regress/sql:
        tsearch.sql (r1.2 -> r1.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/tsearch.sql?r1=1.2&r2=1.3)