Private Threads

[Eikinskjaldi]

I've managed success in porting this hack to my board. I have also added the functionality to choose what forums private threads are allowed in. There are many file edits, though. Additionally, the hack's old problem of showing links to threads one doesn't have access to in the lastpost column persists.

I hope to fix this, minimize the file edits, and add admin options for who has permission override privelages, and perhaps change or add to the types of criteria for private threads before releasing.