vps_parse_config(): better warnings/errors while parsing config

1. s/dup/duplicate/

2. Always say parameter, value, file name and line number, so it's easy
   to track down what's wrong. Compare:

	Warning: dup for LOGGING=no in line 9 is ignored
   and
	Warning at /etc/vz/vz.conf:9: duplicate for LOGGING ("no"), ignored

3. Unify messages (was/is// etc)

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
1 file changed