Improve COPY syntax to use WITH clause, keep backward compatibility.

doc/src/sgml/keywords.sgml

doc/src/sgml/ref/copy.sgml

doc/src/sgml/ref/psql-ref.sgml

src/backend/commands/copy.c

src/backend/commands/dbcommands.c

src/backend/nodes/copyfuncs.c

src/backend/nodes/equalfuncs.c

src/backend/parser/gram.y

src/backend/parser/keywords.c

src/backend/tcop/utility.c

src/bin/pgaccess/doc/html/tutorial/tut_edit.html

src/bin/pgaccess/lib/help/copy.hlp

src/bin/pgaccess/lib/mainlib.tcl

src/bin/psql/copy.c

src/include/commands/copy.h

src/include/commands/dbcommands.h

src/include/nodes/parsenodes.h

...nterfaces/jdbc/org/postgresql/jdbc1/DatabaseMetaData.java

...nterfaces/jdbc/org/postgresql/jdbc2/DatabaseMetaData.java

src/test/locale/de_DE.ISO8859-1/test-de-upper.sql.in