When forecasting node usage, explicitly show everything free at time 0.

This seems better in the case when there are no experiments and no
reservations using the node type in question (formerly we would just
return an empty list... not very useful), and arguably better in less
trivial cases, too.

db/Reservation.pm.in

@@ -665,6 +665,14 @@ sub IsFeasible($$;$$$$$)
 	push( @timeline, $end ) if( defined( $end->{'t'} ) );
     }
 
+    if( defined( $forecast ) ) {
+	my %origin = (
+	    t => 0,
+	    free => $free
+	    );
+	push( @$forecast, \%origin );
+    }
+
     my @events = sort { $a->{'t'} <=> $b->{'t'} } @timeline;
     
     foreach my $event ( @events ) {