Conveyancing — Contract for sale — Certificates and inspections — Deposit —Rescission — COSTS — Party/Party — Exceptions to general rule that costs follow the event — Offers of compromise/Calderbank offers — where contract for sale did not annex a swimming pool compliance certificate — whether s 52A(4) of the Conveyancing Act 1919 (NSW) avoids a special condition purporting to vary the requirement to annex a swimming pool certificate — whether the purchaser validly rescinded the contract — whether deposit should be returned to the purchaser — whether indemnity costs should be ordered where a Calderbank offer was made