A Link creates a portal which can be used to connect to another web space or page specified with a URL.
draw_glow (default "true") - whether to show the portal glow along the boundary
draw_text (default "true") - whether to show the text at the top of the portal for URL and page title
auto_load (default "false") - if true, the room that the portal links to will be loaded immediately; if false, the portal must first be clicked before it will load the room
thumb_id (default "") - if set to the id of an AssetImage, a "thumbnail image" will be displayed for the portal, useful for indicating what lies through it before it's loaded. The AssetImage content is expected to be square (width and height equal), and the portal will crop the image according to its dimensions to preserve the aspect ratio.
mirror (default "false") - Boolean that determines whether or not the portal will be a mirror. To mirror the room's contents, the url of the link must be that of the containing room.