make lower_resultion's parameters optional

Signed-off-by: Mattias Andrée <maandree@operamail.com>
improve print_curves with compact parameters + fix lower_resolution

Signed-off-by: Mattias Andrée <maandree@operamail.com>
improve lower_resolution and add the comprehensive test

Signed-off-by: Mattias Andrée <maandree@operamail.com>
update info with lower_resolution

Signed-off-by: Mattias Andrée <maandree@operamail.com>