Slice a single object with multiple layer heights. :-)

lib/Slic3r/Model.pm

@@ -81,6 +81,7 @@ has 'model'     => (is => 'ro', weak_ref => 1, required => 1);
 has 'vertices'  => (is => 'ro', default => sub { [] });
 has 'volumes'   => (is => 'ro', default => sub { [] });
 has 'instances' => (is => 'rw');
+has 'layer_height_ranges' => (is => 'rw', default => sub { [] }); # [ z_min, z_max, layer_height ]
 
 sub add_volume {
     my $self = shift;