#18 Make it easy to remove room list panel

[Daniel Howard]

A developer should be able to comment out a few lines of code to remove the room list panel and not get any JavaScript errors.

Right now, other components update HTML elements inside the room list panel without checking if they exist. If a non-existent HTML element is updated, a JavaScript error occurs and everything stops running. It would be better to check to see if the HTML element exists first and, only if it does, then update it.

Other windows and objects similar to the room list panel could be improved, too.