pgsql-server: Remove arithmetic operators on the 1-byte-char datatype,

Log Message:
-----------
Remove arithmetic operators on the 1-byte-char datatype, as per proposals
made several times in the past. Add coercion functions between "char"
and integer so that a workaround is possible if needed.

Initdb forced.

Modified Files:
--------------
pgsql-server/doc/src/sgml:
release.sgml (r1.299 -> r1.300)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/release.sgml.diff?r1=1.299&r2=1.300)
pgsql-server/src/backend/utils/adt:
char.c (r1.40 -> r1.41)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/utils/adt/char.c.diff?r1=1.40&r2=1.41)
pgsql-server/src/include/catalog:
catversion.h (r1.249 -> r1.250)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/catalog/catversion.h.diff?r1=1.249&r2=1.250)
pg_cast.h (r1.15 -> r1.16)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/catalog/pg_cast.h.diff?r1=1.15&r2=1.16)
pg_operator.h (r1.128 -> r1.129)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/catalog/pg_operator.h.diff?r1=1.128&r2=1.129)
pg_proc.h (r1.346 -> r1.347)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/catalog/pg_proc.h.diff?r1=1.346&r2=1.347)
pgsql-server/src/include/utils:
builtins.h (r1.250 -> r1.251)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/utils/builtins.h.diff?r1=1.250&r2=1.251)