update b8 to version 0.6.1

This commit updates the b8 files (used in comment spam detector) to [version 0.6.1](http://nasauber.de/blog/T/142/b8_0.6.1).
Neither interfaces nor database formats have changed, so this should not cause any troubles.

Class b8_storage_mysql does not get updated during this commit, because our implementation already uses PDO_MySQL instead of the old mysql API used by the offical b8 codebase's class and the fix for the potential SQL injection is already included in our PDO version.