config.inc.php:
- add note that $CONF[vacation_domain] can't be used for "normal" mails

model/DomainHandler.php:
- validate_new_id(): 
  - error out when trying to add $CONF[vacation_domain]
  - some whitespace fixes
- remove superfluous comment on initStruct()

*.lang:
- add 'domain_conflict_vacation_domain' error message



git-svn-id: svn://svn.code.sf.net/p/postfixadmin/code@1694 a1433add-5e2c-0410-b055-b7f2511e0802