# setzt HTTP Header
sub header{
	my $self = shift;
	my %header = @_;
	%{$self->{HEADERS}} = (%{$self->{HEADERS}}, %header) if @_;
	my @hs = ();
	# Default Header Content-Type sicherstellen
	if(not exists $self->{HEADERS}{'Content-Type'}){
		$self->{HEADERS}{'Content-Type'} = 'text/html; charset=UTF-8';
	}
	foreach my $h(keys %{$self->{HEADERS}}){
		push @hs, "$h: $self->{HEADERS}{$h}";
	}
	return join("\n", @hs)."\n\n";
}