- Always entity render name, and fallback to "N/A" if no name is avaialble

- Clear previous messages, if character sheet is empty (i.e. test mode)
- Refactor out generate_chat() and generate_character() so they can be called from different packets more easily
- Don't allow chats with entities that have no character sheet generated - keep trying to generate a new character sheet (needed for test mode)
- Don't ever set "N/A" as an actual customName