The screen for adding new bans and modifying existing ones.

• Adding new bans:
• Accesssed by ?action=ban;sa=add.
• Uses the ban_edit sub template of the ManageBans template.
• Modifying existing bans:
• Accesssed by ?action=ban;sa=edit;bg=x
• Uses the ban_edit sub template of the ManageBans template.
• Shows a list of ban triggers for the specified ban.
• Handles submitted forms that add, modify or remove ban triggers.