public static void RegisterGenerator( [NotNull] MapGenerator gen ) {
if( gen == null ) {
throw new ArgumentNullException( "gen" );
}
if( GetGeneratorByName( gen.Name ) != null ) {
throw new ArgumentException( "A generator with the same name has already been registered." );
}
Generators.Add( gen.Name.ToLowerInvariant(), gen );
WorldCommands.CdSetGen.Help += " " + gen.Name;
WorldCommands.CdSetGen.HelpSections.Add( gen.Name.ToLowerInvariant(), gen.Help );
WorldCommands.CdGen.HelpSections.Add( gen.Name.ToLowerInvariant(), gen.Help );
}