Add support for YouTube Live chat, IRC servers, etc

[Hotrian]

It goes against the current title of this application, but it would be great if other chats were supported too. It shouldn't be too hard to incorporate other chat options, but the UI needs a serious overhaul before these can be cleanly implemented.

It's on the list of things to do ;]

If you have a suggestion for chats to implement, feel free to mention them below and I'll see what I can do when the time comes.

[Hotrian]

Now that I've also opened OpenVRDesktopDisplayPortal to the public, I'm considering consolidating these and future overlay utilities into a single application with a level select menu. It might happen eventually ;]