- added some comments to the auth class for better understanding
- revised some permission functions
- added option to negate permission check by prefixing option with a ! (for example checking for !f_read returns true if user is not able to read forum)
- used the new option for testing in ucp front
git-svn-id: file:///svn/phpbb/trunk@5423 89ea8834-ac86-4346-8a33-228a782c2dd0