Mostly chat-related improvements, mainly adding chattags (icons) to important channels

Also doing some cleanups and other minor changes. Read the commits, they are detailed.

Stuff changed includes:
* Chat tags, chat tags everywhere
* New ready button
* Better main menu size
* Adminhelps can now be typed in 'console' and have a confirmation
* Radio color changes
* Moved a lot of formatting stuff to stylesheet and generally cleaned up the chat output code, trying to have a unified format for messages
* Analyze-air additionaly shows temperature in Kelvin
* Posibrain confirmation if you really want to join
* Dead chat announcements if someone leaves, and basically a dead chat say code rewrite. It all uses one (arguably messy) proc instead of many lines of similar (definetly messy) code. Admins can now JMP to dead chat, ghosts can follow other ghosts, and it works both for say and emotes (because they use the same code now).