pgsql: This patch makes the error message strings throughout the backend

Log Message:
-----------
This patch makes the error message strings throughout the backend
more compliant with the error message style guide. In particular,
errdetail should begin with a capital letter and end with a period,
whereas errmsg should not. I also fixed a few related issues in
passing, such as fixing the repeated misspelling of "lexeme" in
contrib/tsearch2 (per Tom's suggestion).

Modified Files:
--------------
    pgsql/contrib/cube:
        cubeparse.y (r1.13 -> r1.14)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/cube/cubeparse.y.diff?r1=1.13&r2=1.14)
    pgsql/contrib/intarray:
        _int_gist.c (r1.9 -> r1.10)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/intarray/_int_gist.c.diff?r1=1.9&r2=1.10)
    pgsql/contrib/isbn_issn:
        isbn_issn.c (r1.7 -> r1.8)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/isbn_issn/isbn_issn.c.diff?r1=1.7&r2=1.8)
    pgsql/contrib/ltree:
        lquery_op.c (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/ltree/lquery_op.c.diff?r1=1.8&r2=1.9)
        ltree.h (r1.13 -> r1.14)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/ltree/ltree.h.diff?r1=1.13&r2=1.14)
        ltree_io.c (r1.10 -> r1.11)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/ltree/ltree_io.c.diff?r1=1.10&r2=1.11)
        ltxtquery_io.c (r1.9 -> r1.10)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/ltree/ltxtquery_io.c.diff?r1=1.9&r2=1.10)
        ltxtquery_op.c (r1.4 -> r1.5)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/ltree/ltxtquery_op.c.diff?r1=1.4&r2=1.5)
    pgsql/contrib/pg_trgm:
        trgm_gist.c (r1.5 -> r1.6)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_trgm/trgm_gist.c.diff?r1=1.5&r2=1.6)
        trgm_op.c (r1.3 -> r1.4)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_trgm/trgm_op.c.diff?r1=1.3&r2=1.4)
    pgsql/contrib/tablefunc:
        tablefunc.c (r1.39 -> r1.40)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tablefunc/tablefunc.c.diff?r1=1.39&r2=1.40)
    pgsql/contrib/tsearch2:
        prs_dcfg.c (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/prs_dcfg.c.diff?r1=1.8&r2=1.9)
        query.c (r1.23 -> r1.24)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/query.c.diff?r1=1.23&r2=1.24)
        query_cleanup.c (r1.1 -> r1.2)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/query_cleanup.c.diff?r1=1.1&r2=1.2)
        query_gist.c (r1.5 -> r1.6)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/query_gist.c.diff?r1=1.5&r2=1.6)
        query_rewrite.c (r1.4 -> r1.5)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/query_rewrite.c.diff?r1=1.4&r2=1.5)
        ts_cfg.c (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/ts_cfg.c.diff?r1=1.16&r2=1.17)
        ts_stat.c (r1.14 -> r1.15)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/ts_stat.c.diff?r1=1.14&r2=1.15)
        tsvector.c (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/tsvector.c.diff?r1=1.16&r2=1.17)
        wparser.c (r1.10 -> r1.11)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/wparser.c.diff?r1=1.10&r2=1.11)
    pgsql/contrib/tsearch2/docs:
        tsearch-V2-intro.html (r1.6 -> r1.7)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/docs/tsearch-V2-intro.html.diff?r1=1.6&r2=1.7)
        tsearch2-guide.html (r1.1 -> r1.2)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/docs/tsearch2-guide.html.diff?r1=1.1&r2=1.2)
    pgsql/contrib/tsearch2/ispell:
        spell.c (r1.29 -> r1.30)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/ispell/spell.c.diff?r1=1.29&r2=1.30)
    pgsql/contrib/xml2:
        xpath.c (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/xml2/xpath.c.diff?r1=1.8&r2=1.9)
        xslt_proc.c (r1.4 -> r1.5)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/xml2/xslt_proc.c.diff?r1=1.4&r2=1.5)
    pgsql/doc/src/sgml:
        plperl.sgml (r2.49 -> r2.50)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/plperl.sgml.diff?r1=2.49&r2=2.50)
    pgsql/src/backend/access/transam:
        slru.c (r1.34 -> r1.35)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/slru.c.diff?r1=1.34&r2=1.35)
    pgsql/src/backend/port:
        sysv_shmem.c (r1.44 -> r1.45)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/sysv_shmem.c.diff?r1=1.44&r2=1.45)
    pgsql/src/pl/plpython:
        plpython.c (r1.73 -> r1.74)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/plpython.c.diff?r1=1.73&r2=1.74)
    pgsql/src/tutorial:
        beard.c (r1.13 -> r1.14)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/tutorial/beard.c.diff?r1=1.13&r2=1.14)