Fix for #4052: Chaplain's bible spawn easily breaks.

I moved the religion setup to be inside bible code. Chaplains start off with the prompt open like old behavior, but if they disconnect, they can continue by just using a bible.

There is some weirdness with (ab)using hud_used. I'm using it as a semi-reliable check to make sure that you don't already have the input prompt open. If I didn't, you could multi-use the book to spam name change prompts. I can't just put a boolean before and after input() because a disconnection crashes the proc.
Only Chaplains should be able to change the religion, otherwise I can print a bible and change it.