Allow players to remove towns

[Rumsfield]

Add a core.yml option to set whether players can remove towns, or if only admins can (default).

Player town removal

• Players that are the lord of a town can remove it with a chat command under /k town, or with an icon in the town's management menu.
• Players that are kingdom masters can remove any town from their kingdom with a chat command under /k kingdom, or from the kingdom menu.
  • Add a new menu page view to the kingdom menu for only the kingdom master which lists every town. Clicking on a town will remove it from the kingdom.
• Removing a town from the kingdom, either as the town lord or kingdom master, deletes the town including all land claims and monument structure.