Label CVS tip as 8.0devel instead of 7.5devel. Adjust various comments

configure

configure.in

contrib/tsearch/README.tsearch

contrib/tsearch2/README.tsearch2

contrib/tsearch2/docs/tsearch-V2-intro.html

doc/FAQ_SCO

doc/TODO

doc/bug.template

doc/src/sgml/func.sgml

doc/src/sgml/ref/create_table_as.sgml

doc/src/sgml/ref/select_into.sgml

doc/src/sgml/release.sgml

src/backend/access/transam/xlog.c

src/backend/catalog/catalog.c

src/backend/commands/indexcmds.c

src/backend/libpq/be-fsstubs.c

src/backend/nodes/list.c

src/backend/optimizer/path/costsize.c

src/backend/optimizer/path/indxpath.c

src/backend/optimizer/util/pathnode.c