Ability to only display maps made for Xonotic

[Calinou]

The ability to only display maps specifically made for Xonotic (as opposed to maps made for Quake 3 Arena, for example) would be helpful for server owners who want to install visually appealing maps which match the art style of the game.

[z]

One issue with the current dataset, is that the parsing is "destructive" in the sense that when it maps the entities during parsing, it doesn't store their original value, but rather the normalized Xonotic value. The change will require a change to the database schema, as well as the parser.

Beyond that, I need to figure out other ways to assume a Xonotic map, because I don't believe they are specified anywhere explicitly. I'm open to feedback on this front.