#403 markable signs need to be implemented

I've got the basic system working. Write to db, and display correct data.

Unfinished: Reloading the sign so the change in owner is displayed w/o zoning. Timer to check if the sign can be marked again yet.

This change will require a DB update.

ALTER TABLE spawn_signs ADD COLUMN char_id INT UNSIGNED NULL DEFAULT '0' AFTER language, ADD COLUMN char_name VARCHAR(50) NULL DEFAULT NULL AFTER char_id;