local server for easier usage

Created by: deadlocker8

• option in settings
• explain pros/cons
• update wiki
• download server
• create server settings from client
• start BudgetMasterServer.jar from client (if not running)
• add modals for download and starting
• what happens after update of client?
  • auto-update local server as well
  • check compatibility of server and client (update server instead of "you have to manually..."-warning)