Re-written disclaimer

- The original disclaimer violates the end tag nesting rules
- There were two different disclaimers for both languages
Fixed several issues
Fixed comments
Update AbstractUserNotificationEvent.class.php

Permissions and options for events should be evaluated by default (may be overwritten by derived classes)

Currently notification settings for conversations are displayed even if module is disabled (not to speak about problems with my own optional notifications)
Replaced deprecated methods

Replace deprecated methods of StringUtil with their php internal
equivalents. I had to open a new pull request, because i have no idea
how to update the old one :p
Add missing checks for 3rdParty login data

see:  http://beta.woltlab.com/index.php/Thread/3315-Facebook-Register-Fehler/
Merge pull request #1489 from SoftCreatR/deprecated

Replace deprecated methods
Removed FileUtil::unifyDirSeperator()

Please use FileUtil::unifyDirSeparator() instead, notice the spelling error in the original method name.
Merge branch 'master' of github.com:WoltLab/WCF
Fixes code formatting
Merge pull request #1463 from ray176/VersionableDatabaseObject_2

VersionableDatabaseObjects - again
Merge pull request #1475 from michel160/patch-4

Update AbstractUserNotificationEvent.class.php
Merge pull request #1375 from SoftCreatR/disclaimer

Re-write disclaimer