Removes rooms, replaced with cv_advertise and "Advertise" on the host menu.

According to the new API, SRB2APPLICATION is sent instead of MODID. A contact
field was added, but there is no means of accessing it or setting it.

As a slight change, the server list will be populated even on an outdated
version of the game. (The new API was designed with this in mind.) The update
alert is still presented first of course.

HMS lives on in our hearts!

Your server's address is gathered from the request, so it needs to be IPv4!

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

This took fucking ages and it still fails sometimes in edge cases, but I
don't give a FUCK right now.

Cvars:

http_masterserver is the url to the master server's API.
masterserver_token may be an authentication token.